diff --git a/.changeset/tame-islands-enjoy.md b/.changeset/tame-islands-enjoy.md
new file mode 100644
index 0000000000..8e73cc6cfc
--- /dev/null
+++ b/.changeset/tame-islands-enjoy.md
@@ -0,0 +1,6 @@
+---
+'@finos/legend-application-studio': patch
+'@finos/legend-graph': patch
+---
+
+Support Relation Function class mapping in Studio.
diff --git a/packages/legend-application-studio/src/components/editor/editor-group/function-activator/FunctionEditor.tsx b/packages/legend-application-studio/src/components/editor/editor-group/function-activator/FunctionEditor.tsx
index 21201e09f1..469f98fa35 100644
--- a/packages/legend-application-studio/src/components/editor/editor-group/function-activator/FunctionEditor.tsx
+++ b/packages/legend-application-studio/src/components/editor/editor-group/function-activator/FunctionEditor.tsx
@@ -104,6 +104,7 @@ import {
   DatabaseType,
   RelationalDatabaseConnection,
   type FunctionActivator,
+  GenericType,
 } from '@finos/legend-graph';
 import {
   type ApplicationStore,
@@ -120,7 +121,7 @@ import {
 } from '@finos/legend-lego/graph-editor';
 import { getElementIcon } from '../../../ElementIconUtils.js';
 import {
-  function_setReturnType,
+  function_setReturnGenericType,
   function_setReturnMultiplicity,
   function_addParameter,
   function_deleteParameter,
@@ -502,7 +503,7 @@ const ReturnTypeEditor = observer(
       editorStore.graphManagerState.usableClassPropertyTypes.map(
         buildElementOption,
       );
-    const typeName = getFunctionParameterType(returnType.value);
+    const typeName = getFunctionParameterType(returnType.value.rawType);
     const filterOption = createFilter({
       ignoreCase: true,
       ignoreAccents: false,
@@ -510,21 +511,24 @@ const ReturnTypeEditor = observer(
         option.data.value.path,
     });
     const selectedType = {
-      value: returnType.value,
-      label: returnType.value.name,
+      value: returnType.value.rawType,
+      label: returnType.value.rawType.name,
     };
     const changeType = (val: PackageableElementOption<Type>): void => {
-      function_setReturnType(functionElement, val.value);
+      function_setReturnGenericType(
+        functionElement,
+        new GenericType(val.value),
+      );
       setIsEditingType(false);
       updateFunctionName(editorStore, applicationStore, functionElement);
     };
 
     const openElement = (): void => {
-      if (!(returnType.value instanceof PrimitiveType)) {
+      if (!(returnType.value.rawType instanceof PrimitiveType)) {
         editorStore.graphEditorMode.openElement(
-          returnType.value instanceof Unit
-            ? returnType.value.measure
-            : returnType.value,
+          returnType.value.rawType instanceof Unit
+            ? returnType.value.rawType.measure
+            : returnType.value.rawType,
         );
       }
     };
@@ -597,11 +601,11 @@ const ReturnTypeEditor = observer(
           >
             {typeName !== FUNCTION_PARAMETER_TYPE.PRIMITIVE && (
               <div className="property-basic-editor__type__abbr">
-                {getElementIcon(returnType.value, editorStore)}
+                {getElementIcon(returnType.value.rawType, editorStore)}
               </div>
             )}
             <div className="property-basic-editor__type__label">
-              {returnType.value.name}
+              {returnType.value.rawType.name}
             </div>
             <div
               className="property-basic-editor__type__label property-basic-editor__type__label--hover"
@@ -635,11 +639,11 @@ const ReturnTypeEditor = observer(
           >
             {typeName !== FUNCTION_PARAMETER_TYPE.PRIMITIVE && (
               <div className="property-basic-editor__type__abbr">
-                {getElementIcon(returnType.value, editorStore)}
+                {getElementIcon(returnType.value.rawType, editorStore)}
               </div>
             )}
             <div className="property-basic-editor__type__label">
-              {returnType.value.name}
+              {returnType.value.rawType.name}
             </div>
             {typeName !== FUNCTION_PARAMETER_TYPE.PRIMITIVE && (
               <button
diff --git a/packages/legend-application-studio/src/components/editor/editor-group/uml-editor/ClassQueryBuilder.tsx b/packages/legend-application-studio/src/components/editor/editor-group/uml-editor/ClassQueryBuilder.tsx
index dd01bab989..0bfe6eacd3 100644
--- a/packages/legend-application-studio/src/components/editor/editor-group/uml-editor/ClassQueryBuilder.tsx
+++ b/packages/legend-application-studio/src/components/editor/editor-group/uml-editor/ClassQueryBuilder.tsx
@@ -25,6 +25,8 @@ import {
   ELEMENT_PATH_DELIMITER,
   RawVariableExpression,
   getFunctionSignature,
+  GenericTypeExplicitReference,
+  GenericType,
 } from '@finos/legend-graph';
 import {
   type QueryBuilderState,
@@ -118,7 +120,7 @@ export const promoteQueryToFunction = async (
     const returnType = queryBuilderState.getQueryReturnType();
     const _function = new ConcreteFunctionDefinition(
       functionName, // use functionName for now and it will be reset after composing _function.parameters and _function.returnType
-      PackageableElementExplicitReference.create(returnType),
+      GenericTypeExplicitReference.create(new GenericType(returnType)),
       Multiplicity.ONE,
     );
     // we will copy the body of the query to the body of the function and extract the parameters out
diff --git a/packages/legend-application-studio/src/stores/editor/NewElementState.ts b/packages/legend-application-studio/src/stores/editor/NewElementState.ts
index a015f30c7f..ac19159bc9 100644
--- a/packages/legend-application-studio/src/stores/editor/NewElementState.ts
+++ b/packages/legend-application-studio/src/stores/editor/NewElementState.ts
@@ -82,6 +82,8 @@ import {
   generateIdentifiedConnectionId,
   getMappingCompatibleRuntimes,
   RuntimePointer,
+  GenericTypeExplicitReference,
+  GenericType,
 } from '@finos/legend-graph';
 import type { DSL_Mapping_LegendStudioApplicationPlugin_Extension } from '../extensions/DSL_Mapping_LegendStudioApplicationPlugin_Extension.js';
 import {
@@ -949,7 +951,9 @@ export class NewElementState {
       case PACKAGEABLE_ELEMENT_TYPE.FUNCTION: {
         const fn = new ConcreteFunctionDefinition(
           name,
-          PackageableElementExplicitReference.create(PrimitiveType.STRING),
+          GenericTypeExplicitReference.create(
+            new GenericType(PrimitiveType.STRING),
+          ),
           Multiplicity.ONE,
         );
         // default to empty string
diff --git a/packages/legend-application-studio/src/stores/editor/editor-state/element-editor-state/function-activator/testable/FunctionTestableState.ts b/packages/legend-application-studio/src/stores/editor/editor-state/element-editor-state/function-activator/testable/FunctionTestableState.ts
index ecbf5f3fbe..4173ed5b66 100644
--- a/packages/legend-application-studio/src/stores/editor/editor-state/element-editor-state/function-activator/testable/FunctionTestableState.ts
+++ b/packages/legend-application-studio/src/stores/editor/editor-state/element-editor-state/function-activator/testable/FunctionTestableState.ts
@@ -591,7 +591,7 @@ export const createFunctionTest = (
   } else {
     const equalTo = new EqualTo();
     equalTo.id = DEFAULT_TEST_ASSERTION_ID;
-    const type = functionDefinition.returnType.value;
+    const type = functionDefinition.returnType.value.rawType;
     const valSpec = buildDefaultInstanceValue(
       editorStore.graphManagerState.graph,
       type,
diff --git a/packages/legend-application-studio/src/stores/editor/editor-state/element-editor-state/mapping/MappingEditorState.ts b/packages/legend-application-studio/src/stores/editor/editor-state/element-editor-state/mapping/MappingEditorState.ts
index f45cd391c4..b7f5262f2d 100644
--- a/packages/legend-application-studio/src/stores/editor/editor-state/element-editor-state/mapping/MappingEditorState.ts
+++ b/packages/legend-application-studio/src/stores/editor/editor-state/element-editor-state/mapping/MappingEditorState.ts
@@ -102,6 +102,7 @@ import {
   type Store,
   ModelStore,
   INTERNAL__UnknownSetImplementation,
+  RelationFunctionInstanceSetImplementation,
 } from '@finos/legend-graph';
 import type {
   DSL_Mapping_LegendStudioApplicationPlugin_Extension,
@@ -312,6 +313,12 @@ export const getMappingElementSource = (
       plugins,
     );
   }
+  // TODO: We could probably return the relation function used for the mapping here once we implement the form mode support for it
+  else if (
+    mappingElement instanceof RelationFunctionInstanceSetImplementation
+  ) {
+    return undefined;
+  }
   const extraMappingElementSourceExtractors = plugins.flatMap(
     (plugin) =>
       (
@@ -900,6 +907,12 @@ export class MappingEditorState extends ElementEditorState {
       );
       return;
     }
+    if (mappingElement instanceof RelationFunctionInstanceSetImplementation) {
+      this.editorStore.applicationStore.notificationService.notifyUnsupportedFeature(
+        'Relation Function mapping editor',
+      );
+      return;
+    }
     // Open mapping element from included mapping in another mapping editor tab
     if (mappingElement._PARENT !== this.element) {
       this.editorStore.graphEditorMode.openElement(mappingElement._PARENT);
diff --git a/packages/legend-application-studio/src/stores/editor/editor-state/element-editor-state/mapping/MappingElementDecorator.ts b/packages/legend-application-studio/src/stores/editor/editor-state/element-editor-state/mapping/MappingElementDecorator.ts
index 1fc1365cbf..193150df92 100644
--- a/packages/legend-application-studio/src/stores/editor/editor-state/element-editor-state/mapping/MappingElementDecorator.ts
+++ b/packages/legend-application-studio/src/stores/editor/editor-state/element-editor-state/mapping/MappingElementDecorator.ts
@@ -65,6 +65,7 @@ import {
   EnumerationMappingExplicitReference,
   SetImplementationExplicitReference,
   type INTERNAL__UnknownSetImplementation,
+  type RelationFunctionInstanceSetImplementation,
 } from '@finos/legend-graph';
 import type { EditorStore } from '../../../EditorStore.js';
 import {
@@ -657,6 +658,12 @@ export class MappingElementDecorator implements SetImplementationVisitor<void> {
   ): void {
     return;
   }
+
+  visit_RelationFunctionInstanceSetImplementation(
+    setImplementation: RelationFunctionInstanceSetImplementation,
+  ): void {
+    return;
+  }
 }
 
 /**
@@ -803,4 +810,10 @@ export class MappingElementDecorationCleaner
   ): void {
     return;
   }
+
+  visit_RelationFunctionInstanceSetImplementation(
+    setImplementation: RelationFunctionInstanceSetImplementation,
+  ): void {
+    return;
+  }
 }
diff --git a/packages/legend-application-studio/src/stores/graph-modifier/DomainGraphModifierHelper.ts b/packages/legend-application-studio/src/stores/graph-modifier/DomainGraphModifierHelper.ts
index 0d7bc5550a..2809a05018 100644
--- a/packages/legend-application-studio/src/stores/graph-modifier/DomainGraphModifierHelper.ts
+++ b/packages/legend-application-studio/src/stores/graph-modifier/DomainGraphModifierHelper.ts
@@ -27,7 +27,6 @@ import {
   type GenericTypeReference,
   type TaggedValue,
   type StereotypeReference,
-  type Type,
   type Multiplicity,
   type Stereotype,
   type Tag,
@@ -68,7 +67,6 @@ import {
   observe_TaggedValue,
   observe_Constraint,
   observe_GenericType,
-  observe_Type,
   observe_Unit,
   observe_RawLambda,
   isStubbed_PackageableElement,
@@ -365,9 +363,9 @@ export const function_addParameter = action(
     addUniqueEntry(_func.parameters, observe_RawVariableExpression(val));
   },
 );
-export const function_setReturnType = action(
-  (_func: ConcreteFunctionDefinition, val: Type): void => {
-    packageableElementReference_setValue(_func.returnType, observe_Type(val));
+export const function_setReturnGenericType = action(
+  (_func: ConcreteFunctionDefinition, val: GenericType): void => {
+    setGenericTypeReferenceValue(_func.returnType, observe_GenericType(val));
   },
 );
 export const function_setReturnMultiplicity = action(
diff --git a/packages/legend-graph/src/graph-manager/__tests__/roundtripTestData/TEST_DATA__DomainRoundtrip.ts b/packages/legend-graph/src/graph-manager/__tests__/roundtripTestData/TEST_DATA__DomainRoundtrip.ts
index fb7f1b3962..c1668c1942 100644
--- a/packages/legend-graph/src/graph-manager/__tests__/roundtripTestData/TEST_DATA__DomainRoundtrip.ts
+++ b/packages/legend-graph/src/graph-manager/__tests__/roundtripTestData/TEST_DATA__DomainRoundtrip.ts
@@ -888,7 +888,7 @@ export const TEST_DATA__FunctionRoundtrip = [
           genericType: {
             rawType: {
               _type: 'packageableType',
-              fullPath: 'tClass',
+              fullPath: 'test::tClass',
             },
           },
           multiplicity: {
@@ -902,7 +902,7 @@ export const TEST_DATA__FunctionRoundtrip = [
           genericType: {
             rawType: {
               _type: 'packageableType',
-              fullPath: 'tClass',
+              fullPath: 'test::tClass',
             },
           },
           multiplicity: {
@@ -921,7 +921,7 @@ export const TEST_DATA__FunctionRoundtrip = [
       returnGenericType: {
         rawType: {
           _type: 'packageableType',
-          fullPath: 'tClass',
+          fullPath: 'test::tClass',
         },
       },
       stereotypes: [
diff --git a/packages/legend-graph/src/graph-manager/action/changeDetection/DSL_Mapping_ObserverHelper.ts b/packages/legend-graph/src/graph-manager/action/changeDetection/DSL_Mapping_ObserverHelper.ts
index 91ec40bcad..81d98b88e5 100644
--- a/packages/legend-graph/src/graph-manager/action/changeDetection/DSL_Mapping_ObserverHelper.ts
+++ b/packages/legend-graph/src/graph-manager/action/changeDetection/DSL_Mapping_ObserverHelper.ts
@@ -132,6 +132,8 @@ import type { INTERNAL__UnknownConnection } from '../../../graph/metamodel/pure/
 import type { INTERNAL__UnknownPropertyMapping } from '../../../graph/metamodel/pure/packageableElements/mapping/INTERNAL__UnknownPropertyMapping.js';
 import type { INTERNAL__UnknownSetImplementation } from '../../../graph/metamodel/pure/packageableElements/mapping/INTERNAL__UnknownSetImplementation.js';
 import type { INTERNAL__UnknownStore } from '../../../graph/metamodel/pure/packageableElements/store/INTERNAL__UnknownStore.js';
+import type { RelationFunctionInstanceSetImplementation } from '../../../graph/metamodel/pure/packageableElements/mapping/relationFunction/RelationFunctionInstanceSetImplementation.js';
+import type { RelationFunctionPropertyMapping } from '../../../graph/metamodel/pure/packageableElements/mapping/relationFunction/RelationFunctionPropertyMapping.js';
 
 // ------------------------------------- Store -------------------------------------
 
@@ -396,6 +398,12 @@ class PropertyMappingObserver implements PropertyMappingVisitor<void> {
   visit_XStorePropertyMapping(propertyMapping: XStorePropertyMapping): void {
     // TODO
   }
+
+  visit_RelationFunctionPropertyMapping(
+    propertyMapping: RelationFunctionPropertyMapping,
+  ): void {
+    // TODO
+  }
 }
 
 export const observe_PropertyMapping = (
@@ -636,6 +644,12 @@ class SetImplementationObserver implements SetImplementationVisitor<void> {
     );
   }
 
+  visit_RelationFunctionInstanceSetImplementation(
+    setImplementation: RelationFunctionInstanceSetImplementation,
+  ): void {
+    // TODO
+  }
+
   visit_AggregationAwareSetImplementation(
     setImplementation: AggregationAwareSetImplementation,
   ): void {
diff --git a/packages/legend-graph/src/graph-manager/action/changeDetection/DomainObserverHelper.ts b/packages/legend-graph/src/graph-manager/action/changeDetection/DomainObserverHelper.ts
index 971ecb0b58..924221d7ec 100644
--- a/packages/legend-graph/src/graph-manager/action/changeDetection/DomainObserverHelper.ts
+++ b/packages/legend-graph/src/graph-manager/action/changeDetection/DomainObserverHelper.ts
@@ -540,7 +540,7 @@ export const observe_ConcreteFunctionDefinition = skipObservedWithContext(
     });
 
     metamodel.parameters.forEach(observe_RawVariableExpression);
-    observe_PackageableElementReference(metamodel.returnType);
+    observe_GenericTypeReference(metamodel.returnType);
     metamodel.stereotypes.forEach(observe_StereotypeReference);
     metamodel.taggedValues.forEach(observe_TaggedValue);
     metamodel.tests.forEach((t) => observe_FunctionTestSuite(t, context));
diff --git a/packages/legend-graph/src/graph-manager/protocol/pure/v1/model/packageableElements/mapping/V1_ClassMapping.ts b/packages/legend-graph/src/graph-manager/protocol/pure/v1/model/packageableElements/mapping/V1_ClassMapping.ts
index a088c8527a..9cdbd6a50e 100644
--- a/packages/legend-graph/src/graph-manager/protocol/pure/v1/model/packageableElements/mapping/V1_ClassMapping.ts
+++ b/packages/legend-graph/src/graph-manager/protocol/pure/v1/model/packageableElements/mapping/V1_ClassMapping.ts
@@ -25,6 +25,7 @@ import type { V1_PureInstanceClassMapping } from '../../../model/packageableElem
 import type { V1_RootFlatDataClassMapping } from '../../../model/packageableElements/store/flatData/mapping/V1_RootFlatDataClassMapping.js';
 import type { V1_MergeOperationClassMapping } from './V1_MergeOperationClassMapping.js';
 import type { V1_INTERNAL__UnknownClassMapping } from './V1_INTERNAL__UnknownClassMapping.js';
+import type { V1_RelationFunctionClassMapping } from './V1_RelationFunctionClassMapping.js';
 
 export interface V1_ClassMappingVisitor<T> {
   visit_ClassMapping(classMapping: V1_ClassMapping): T;
@@ -45,6 +46,9 @@ export interface V1_ClassMappingVisitor<T> {
   visit_AggregationAwareClassMapping(
     classMapping: V1_AggregationAwareClassMapping,
   ): T;
+  visit_RelationFunctionClassMapping(
+    classMapping: V1_RelationFunctionClassMapping,
+  ): T;
 }
 
 export abstract class V1_ClassMapping implements Hashable {
diff --git a/packages/legend-graph/src/graph-manager/protocol/pure/v1/model/packageableElements/mapping/V1_PropertyMapping.ts b/packages/legend-graph/src/graph-manager/protocol/pure/v1/model/packageableElements/mapping/V1_PropertyMapping.ts
index 4de9a86d8b..2b918839aa 100644
--- a/packages/legend-graph/src/graph-manager/protocol/pure/v1/model/packageableElements/mapping/V1_PropertyMapping.ts
+++ b/packages/legend-graph/src/graph-manager/protocol/pure/v1/model/packageableElements/mapping/V1_PropertyMapping.ts
@@ -29,6 +29,7 @@ import type { V1_EmbeddedFlatDataPropertyMapping } from '../../../model/packagea
 import type { V1_XStorePropertyMapping } from './xStore/V1_XStorePropertyMapping.js';
 import type { V1_FlatDataAssociationPropertyMapping } from '../../../model/packageableElements/store/flatData/mapping/V1_FlatDataAssociationPropertyMapping.js';
 import type { V1_INTERNAL__UnknownPropertyMapping } from './V1_INTERNAL__UnknownPropertyMapping.js';
+import type { V1_RelationFunctionPropertyMapping } from './V1_RelationFunctionPropertyMapping.js';
 
 export interface V1_PropertyMappingVisitor<T> {
   visit_PropertyMapping(propertyMapping: V1_PropertyMapping): T;
@@ -60,6 +61,9 @@ export interface V1_PropertyMappingVisitor<T> {
   visit_FlatDataAssociationPropertyMapping(
     propertyMapping: V1_FlatDataAssociationPropertyMapping,
   ): T;
+  visit_RelationFunctionPropertyMapping(
+    propertyMapping: V1_RelationFunctionPropertyMapping,
+  ): T;
 }
 
 export abstract class V1_PropertyMapping implements Hashable {
diff --git a/packages/legend-graph/src/graph-manager/protocol/pure/v1/model/packageableElements/mapping/V1_RelationFunctionClassMapping.ts b/packages/legend-graph/src/graph-manager/protocol/pure/v1/model/packageableElements/mapping/V1_RelationFunctionClassMapping.ts
new file mode 100644
index 0000000000..81533a48f9
--- /dev/null
+++ b/packages/legend-graph/src/graph-manager/protocol/pure/v1/model/packageableElements/mapping/V1_RelationFunctionClassMapping.ts
@@ -0,0 +1,60 @@
+/**
+ * Copyright (c) 2020-present, Goldman Sachs
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * Copyright (c) 2025-present, Goldman Sachs
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { CORE_HASH_STRUCTURE } from '../../../../../../../graph/Core_HashUtils.js';
+import type { V1_PropertyMapping } from './V1_PropertyMapping.js';
+import {
+  type V1_ClassMappingVisitor,
+  V1_ClassMapping,
+} from './V1_ClassMapping.js';
+import type { V1_PackageableElementPointer } from '../V1_PackageableElement.js';
+import { hashArray, type Hashable } from '@finos/legend-shared';
+
+export class V1_RelationFunctionClassMapping
+  extends V1_ClassMapping
+  implements Hashable
+{
+  relationFunction!: V1_PackageableElementPointer;
+  propertyMappings: V1_PropertyMapping[] = [];
+
+  accept_ClassMappingVisitor<T>(visitor: V1_ClassMappingVisitor<T>): T {
+    return visitor.visit_RelationFunctionClassMapping(this);
+  }
+
+  override get hashCode(): string {
+    return hashArray([
+      CORE_HASH_STRUCTURE.RELATION_FUNCTION_INSTANCE_SET_IMPLEMENTATION,
+      super.hashCode,
+      hashArray(this.propertyMappings),
+    ]);
+  }
+}
diff --git a/packages/legend-graph/src/graph-manager/protocol/pure/v1/model/packageableElements/mapping/V1_RelationFunctionPropertyMapping.ts b/packages/legend-graph/src/graph-manager/protocol/pure/v1/model/packageableElements/mapping/V1_RelationFunctionPropertyMapping.ts
new file mode 100644
index 0000000000..9d35e6c5d8
--- /dev/null
+++ b/packages/legend-graph/src/graph-manager/protocol/pure/v1/model/packageableElements/mapping/V1_RelationFunctionPropertyMapping.ts
@@ -0,0 +1,57 @@
+/**
+ * Copyright (c) 2020-present, Goldman Sachs
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * Copyright (c) 2025-present, Goldman Sachs
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { hashArray, type Hashable } from '@finos/legend-shared';
+import { CORE_HASH_STRUCTURE } from '../../../../../../../graph/Core_HashUtils.js';
+import {
+  type V1_PropertyMappingVisitor,
+  V1_PropertyMapping,
+} from './V1_PropertyMapping.js';
+
+export class V1_RelationFunctionPropertyMapping
+  extends V1_PropertyMapping
+  implements Hashable
+{
+  column!: string;
+
+  accept_PropertyMappingVisitor<T>(visitor: V1_PropertyMappingVisitor<T>): T {
+    return visitor.visit_RelationFunctionPropertyMapping(this);
+  }
+
+  override get hashCode(): string {
+    return hashArray([
+      CORE_HASH_STRUCTURE.RELATION_FUNCTION_PROPERTY_MAPPING,
+      super.hashCode,
+      this.column,
+    ]);
+  }
+}
diff --git a/packages/legend-graph/src/graph-manager/protocol/pure/v1/transformation/pureGraph/from/V1_DomainTransformer.ts b/packages/legend-graph/src/graph-manager/protocol/pure/v1/transformation/pureGraph/from/V1_DomainTransformer.ts
index 6be74a31e7..82b680eb2a 100644
--- a/packages/legend-graph/src/graph-manager/protocol/pure/v1/transformation/pureGraph/from/V1_DomainTransformer.ts
+++ b/packages/legend-graph/src/graph-manager/protocol/pure/v1/transformation/pureGraph/from/V1_DomainTransformer.ts
@@ -78,6 +78,21 @@ import { V1_DefaultValue } from '../../../model/packageableElements/domain/V1_De
 import { PackageableElementPointerType } from '../../../../../../../graph/MetaModelConst.js';
 import { V1_createGenericTypeWithElementPath } from '../../../helpers/V1_DomainHelper.js';
 import { V1_PackageableElementPointer } from '../../../model/packageableElements/V1_PackageableElement.js';
+import type { GenericType } from '../../../../../../../graph/metamodel/pure/packageableElements/domain/GenericType.js';
+import type { V1_GenericType } from '../../../model/packageableElements/type/V1_GenericType.js';
+
+export const V1_createGenericType = (
+  genericType: GenericType,
+): V1_GenericType => {
+  const protocolGenType = V1_createGenericTypeWithElementPath(
+    genericType.rawType.path,
+  );
+  const typeArguments = genericType.typeArguments ?? [];
+  protocolGenType.typeArguments = typeArguments.map((t) =>
+    V1_createGenericType(t.value),
+  );
+  return protocolGenType;
+};
 
 export const V1_createRawGenericTypeWithElementPath = (
   path: string,
@@ -331,9 +346,7 @@ export const V1_transformFunction = (
         new V1_RawValueSpecificationTransformer(context),
       ) as V1_RawVariable,
   );
-  _function.returnGenericType = V1_createGenericTypeWithElementPath(
-    element.returnType.valueForSerialization ?? '',
-  );
+  _function.returnGenericType = V1_createGenericType(element.returnType.value);
   _function.stereotypes = element.stereotypes.map(V1_transformStereotype);
   _function.taggedValues = element.taggedValues.map(V1_transformTaggedValue);
   _function.returnMultiplicity = V1_transformMultiplicity(
diff --git a/packages/legend-graph/src/graph-manager/protocol/pure/v1/transformation/pureGraph/from/V1_MappingTransformer.ts b/packages/legend-graph/src/graph-manager/protocol/pure/v1/transformation/pureGraph/from/V1_MappingTransformer.ts
index a77eb9e6c9..9bfded47f0 100644
--- a/packages/legend-graph/src/graph-manager/protocol/pure/v1/transformation/pureGraph/from/V1_MappingTransformer.ts
+++ b/packages/legend-graph/src/graph-manager/protocol/pure/v1/transformation/pureGraph/from/V1_MappingTransformer.ts
@@ -16,6 +16,7 @@
 
 import {
   guaranteeNonEmptyString,
+  guaranteeNonNullable,
   IllegalStateError,
   isNonNullable,
   UnsupportedOperationError,
@@ -175,6 +176,11 @@ import { V1_INTERNAL__UnknownPropertyMapping } from '../../../model/packageableE
 import type { INTERNAL__UnknownSetImplementation } from '../../../../../../../graph/metamodel/pure/packageableElements/mapping/INTERNAL__UnknownSetImplementation.js';
 import { V1_INTERNAL__UnknownClassMapping } from '../../../model/packageableElements/mapping/V1_INTERNAL__UnknownClassMapping.js';
 import { V1_PackageableElementPointer } from '../../../model/packageableElements/V1_PackageableElement.js';
+import type { RelationFunctionInstanceSetImplementation } from '../../../../../../../graph/metamodel/pure/packageableElements/mapping/relationFunction/RelationFunctionInstanceSetImplementation.js';
+import type { RelationFunctionPropertyMapping } from '../../../../../../../graph/metamodel/pure/packageableElements/mapping/relationFunction/RelationFunctionPropertyMapping.js';
+import { V1_RelationFunctionPropertyMapping } from '../../../model/packageableElements/mapping/V1_RelationFunctionPropertyMapping.js';
+import { V1_RelationFunctionClassMapping } from '../../../model/packageableElements/mapping/V1_RelationFunctionClassMapping.js';
+import { generateFunctionPrettyName } from '../../../../../../../graph/helpers/PureLanguageHelper.js';
 
 export const V1_transformPropertyReference = (
   element: PropertyReference,
@@ -766,6 +772,25 @@ const transformAggregationAwarePropertyMapping = (
   return propertyMapping;
 };
 
+const transformRelationFunctionPropertyMapping = (
+  element: RelationFunctionPropertyMapping,
+): V1_RelationFunctionPropertyMapping => {
+  const propertyMapping = new V1_RelationFunctionPropertyMapping();
+  propertyMapping.column = element.column.name;
+  propertyMapping.property = V1_transformPropertyReference(element.property);
+  propertyMapping.source =
+    element.sourceSetImplementation.valueForSerialization;
+  propertyMapping.target =
+    element.targetSetImplementation?.valueForSerialization;
+  if (element.localMappingProperty) {
+    propertyMapping.localMappingProperty = transformLocalPropertyInfo(
+      element.localMappingProperty,
+    );
+  }
+  propertyMapping.column = element.column.name;
+  return propertyMapping;
+};
+
 class PropertyMappingTransformer
   implements PropertyMappingVisitor<V1_PropertyMapping>
 {
@@ -885,6 +910,12 @@ class PropertyMappingTransformer
   ): V1_PropertyMapping {
     return transformAggregationAwarePropertyMapping(propertyMapping);
   }
+
+  visit_RelationFunctionPropertyMapping(
+    propertyMapping: RelationFunctionPropertyMapping,
+  ): V1_PropertyMapping {
+    return transformRelationFunctionPropertyMapping(propertyMapping);
+  }
 }
 
 const transformOperationType = (
@@ -1162,6 +1193,37 @@ const transformAggregationAwareSetImplementation = (
   return classMapping;
 };
 
+const transformRelationFunctionInstanceSetImplementation = (
+  element: RelationFunctionInstanceSetImplementation,
+  context: V1_GraphTransformerContext,
+): V1_RelationFunctionClassMapping => {
+  const functionName = generateFunctionPrettyName(
+    guaranteeNonNullable(element.relationFunction),
+    {
+      fullPath: true,
+      spacing: false,
+      notIncludeParamName: true,
+    },
+  );
+
+  const classMapping = new V1_RelationFunctionClassMapping();
+  classMapping.relationFunction = new V1_PackageableElementPointer(
+    PackageableElementPointerType.FUNCTION,
+    functionName,
+  );
+  classMapping.id = mappingElementIdSerializer(element.id);
+  classMapping.class = element.class.valueForSerialization ?? '';
+  classMapping.root = element.root.valueForSerialization;
+
+  classMapping.propertyMappings = transformClassMappingPropertyMappings(
+    element.propertyMappings,
+    false,
+    context,
+  );
+  classMapping.extendsClassMappingId = element.superSetImplementationId;
+  return classMapping;
+};
+
 // NOTE: this needs to be a function to avoid error with using before declaration for embedded property mappings due to the hoisting behavior in ES
 function transformProperyMapping(
   propertyMapping: PropertyMapping,
@@ -1279,6 +1341,15 @@ export class V1_SetImplementationTransformer
     );
   }
 
+  visit_RelationFunctionInstanceSetImplementation(
+    setImplementation: RelationFunctionInstanceSetImplementation,
+  ): V1_ClassMapping | undefined {
+    return transformRelationFunctionInstanceSetImplementation(
+      setImplementation,
+      this.context,
+    );
+  }
+
   /**
    * This test is skipped because we want to temporarily relax graph building algorithm
    * to ease Pure -> Legend migration push.
diff --git a/packages/legend-graph/src/graph-manager/protocol/pure/v1/transformation/pureGraph/to/V1_ClassMappingFirstPassBuilder.ts b/packages/legend-graph/src/graph-manager/protocol/pure/v1/transformation/pureGraph/to/V1_ClassMappingFirstPassBuilder.ts
index da9629aa82..3ac38e574e 100644
--- a/packages/legend-graph/src/graph-manager/protocol/pure/v1/transformation/pureGraph/to/V1_ClassMappingFirstPassBuilder.ts
+++ b/packages/legend-graph/src/graph-manager/protocol/pure/v1/transformation/pureGraph/to/V1_ClassMappingFirstPassBuilder.ts
@@ -52,6 +52,8 @@ import type { V1_MergeOperationClassMapping } from '../../../model/packageableEl
 import { MergeOperationSetImplementation } from '../../../../../../../graph/metamodel/pure/packageableElements/mapping/MergeOperationSetImplementation.js';
 import type { V1_INTERNAL__UnknownClassMapping } from '../../../model/packageableElements/mapping/V1_INTERNAL__UnknownClassMapping.js';
 import { INTERNAL__UnknownSetImplementation } from '../../../../../../../graph/metamodel/pure/packageableElements/mapping/INTERNAL__UnknownSetImplementation.js';
+import type { V1_RelationFunctionClassMapping } from '../../../model/packageableElements/mapping/V1_RelationFunctionClassMapping.js';
+import { RelationFunctionInstanceSetImplementation } from '../../../../../../../graph/metamodel/pure/packageableElements/mapping/relationFunction/RelationFunctionInstanceSetImplementation.js';
 
 const getClassMappingOperationType = (value: string): OperationType =>
   guaranteeNonNullable(
@@ -294,4 +296,20 @@ export class V1_ClassMappingFirstPassBuilder
       );
     return aggragetionAwareInstanceSetImplementation;
   }
+
+  visit_RelationFunctionClassMapping(
+    classMapping: V1_RelationFunctionClassMapping,
+  ): SetImplementation {
+    assertNonEmptyString(
+      classMapping.class,
+      `Relation function class mapping 'class' field is missing or empty`,
+    );
+    const targetClass = this.context.resolveClass(classMapping.class);
+    return new RelationFunctionInstanceSetImplementation(
+      V1_getInferredClassMappingId(targetClass.value, classMapping),
+      this.parent,
+      targetClass,
+      InferableMappingElementRootExplicitValue.create(classMapping.root),
+    );
+  }
 }
diff --git a/packages/legend-graph/src/graph-manager/protocol/pure/v1/transformation/pureGraph/to/V1_ClassMappingSecondPassBuilder.ts b/packages/legend-graph/src/graph-manager/protocol/pure/v1/transformation/pureGraph/to/V1_ClassMappingSecondPassBuilder.ts
index e863dc3acb..d33df011e3 100644
--- a/packages/legend-graph/src/graph-manager/protocol/pure/v1/transformation/pureGraph/to/V1_ClassMappingSecondPassBuilder.ts
+++ b/packages/legend-graph/src/graph-manager/protocol/pure/v1/transformation/pureGraph/to/V1_ClassMappingSecondPassBuilder.ts
@@ -67,6 +67,9 @@ import {
 import type { DSL_Mapping_PureProtocolProcessorPlugin_Extension } from '../../../../extensions/DSL_Mapping_PureProtocolProcessorPlugin_Extension.js';
 import type { V1_MergeOperationClassMapping } from '../../../model/packageableElements/mapping/V1_MergeOperationClassMapping.js';
 import type { V1_INTERNAL__UnknownClassMapping } from '../../../model/packageableElements/mapping/V1_INTERNAL__UnknownClassMapping.js';
+import type { V1_RelationFunctionClassMapping } from '../../../model/packageableElements/mapping/V1_RelationFunctionClassMapping.js';
+import { RelationFunctionInstanceSetImplementation } from '../../../../../../../graph/metamodel/pure/packageableElements/mapping/relationFunction/RelationFunctionInstanceSetImplementation.js';
+import { generateFunctionPrettyName } from '../../../../../../../graph/helpers/PureLanguageHelper.js';
 
 export class V1_ClassMappingSecondPassBuilder
   implements V1_ClassMappingVisitor<void>
@@ -365,4 +368,47 @@ export class V1_ClassMappingSecondPassBuilder
 
     return aggragetionAwareInstanceSetImplementation;
   }
+
+  visit_RelationFunctionClassMapping(
+    classMapping: V1_RelationFunctionClassMapping,
+  ): SetImplementation {
+    assertNonEmptyString(
+      classMapping.class,
+      `Relation function class mapping 'class' field is missing or empty`,
+    );
+    const relationFunctionInstanceSetImplementation = guaranteeType(
+      getOwnClassMappingById(
+        this.parent,
+        V1_getInferredClassMappingId(
+          this.context.resolveClass(classMapping.class).value,
+          classMapping,
+        ).value,
+      ),
+      RelationFunctionInstanceSetImplementation,
+    );
+    relationFunctionInstanceSetImplementation.relationFunction =
+      guaranteeNonNullable(
+        this.context.graph.functions.find(
+          (fn) =>
+            generateFunctionPrettyName(fn, {
+              fullPath: true,
+              spacing: false,
+              notIncludeParamName: true,
+            }).replaceAll(/\s/gu, '') ===
+            classMapping.relationFunction.path.replaceAll(/\s/gu, ''),
+        ),
+      );
+    relationFunctionInstanceSetImplementation.propertyMappings =
+      classMapping.propertyMappings.map((propertyMapping) =>
+        propertyMapping.accept_PropertyMappingVisitor(
+          new V1_PropertyMappingBuilder(
+            this.context,
+            relationFunctionInstanceSetImplementation,
+            relationFunctionInstanceSetImplementation,
+            getAllEnumerationMappings(this.parent),
+          ),
+        ),
+      );
+    return relationFunctionInstanceSetImplementation;
+  }
 }
diff --git a/packages/legend-graph/src/graph-manager/protocol/pure/v1/transformation/pureGraph/to/V1_ElementFirstPassBuilder.ts b/packages/legend-graph/src/graph-manager/protocol/pure/v1/transformation/pureGraph/to/V1_ElementFirstPassBuilder.ts
index b23a8d4d10..5764d7379f 100644
--- a/packages/legend-graph/src/graph-manager/protocol/pure/v1/transformation/pureGraph/to/V1_ElementFirstPassBuilder.ts
+++ b/packages/legend-graph/src/graph-manager/protocol/pure/v1/transformation/pureGraph/to/V1_ElementFirstPassBuilder.ts
@@ -81,6 +81,8 @@ import { INTERNAL__UnknownElement } from '../../../../../../../graph/metamodel/p
 import type { V1_HostedService } from '../../../model/packageableElements/function/V1_HostedService.js';
 import { HostedService } from '../../../../../../../graph/metamodel/pure/packageableElements/function/HostedService.js';
 import { V1_buildFunctionActivatorActions } from './helpers/V1_LegendLambdaHelper.js';
+import { GenericTypeImplicitReference } from '../../../../../../../graph/metamodel/pure/packageableElements/domain/GenericTypeReference.js';
+import { GenericType } from '../../../../../../../graph/metamodel/pure/packageableElements/domain/GenericType.js';
 
 export class V1_ElementFirstPassBuilder
   implements V1_PackageableElementVisitor<PackageableElement>
@@ -438,7 +440,10 @@ export class V1_ElementFirstPassBuilder
     const func = new ConcreteFunctionDefinition(
       name,
       // This is just a stub to fill in when we first create the function
-      PackageableElementImplicitReference.create(PrimitiveType.STRING, ''),
+      GenericTypeImplicitReference.create(
+        PackageableElementImplicitReference.create(PrimitiveType.STRING, ''),
+        new GenericType(PrimitiveType.STRING),
+      ),
       Multiplicity.ZERO_MANY,
     );
     const path = V1_buildFullPath(element.package, name);
diff --git a/packages/legend-graph/src/graph-manager/protocol/pure/v1/transformation/pureGraph/to/V1_ElementSecondPassBuilder.ts b/packages/legend-graph/src/graph-manager/protocol/pure/v1/transformation/pureGraph/to/V1_ElementSecondPassBuilder.ts
index 550d99ad94..0295356ca5 100644
--- a/packages/legend-graph/src/graph-manager/protocol/pure/v1/transformation/pureGraph/to/V1_ElementSecondPassBuilder.ts
+++ b/packages/legend-graph/src/graph-manager/protocol/pure/v1/transformation/pureGraph/to/V1_ElementSecondPassBuilder.ts
@@ -86,10 +86,7 @@ import { V1_buildEmbeddedData } from './helpers/V1_DataElementBuilderHelper.js';
 import { V1_buildTestSuite } from './helpers/V1_TestBuilderHelper.js';
 import { ServiceTestSuite } from '../../../../../../../graph/metamodel/pure/packageableElements/service/ServiceTestSuite.js';
 import { V1_DataElementReference } from '../../../model/data/V1_EmbeddedData.js';
-import {
-  V1_buildFunctionSignature,
-  V1_getGenericTypeFullPath,
-} from '../../../helpers/V1_DomainHelper.js';
+import { V1_buildFunctionSignature } from '../../../helpers/V1_DomainHelper.js';
 import { getFunctionName } from '../../../../../../../graph/helpers/DomainHelper.js';
 import { GraphBuilderError } from '../../../../../../GraphManagerUtils.js';
 import { PostValidation } from '../../../../../../../graph/metamodel/pure/packageableElements/service/PostValidation.js';
@@ -371,8 +368,8 @@ export class V1_ElementSecondPassBuilder
     const func = this.context.currentSubGraph.getOwnFunction(
       V1_buildFullPath(protocol.package, V1_buildFunctionSignature(protocol)),
     );
-    func.returnType = this.context.resolveType(
-      V1_getGenericTypeFullPath(protocol.returnGenericType),
+    func.returnType = this.context.resolveGenericTypeFromProtocol(
+      protocol.returnGenericType,
     );
     func.returnMultiplicity = this.context.graph.getMultiplicity(
       protocol.returnMultiplicity.lowerBound,
diff --git a/packages/legend-graph/src/graph-manager/protocol/pure/v1/transformation/pureGraph/to/V1_GraphBuilderContext.ts b/packages/legend-graph/src/graph-manager/protocol/pure/v1/transformation/pureGraph/to/V1_GraphBuilderContext.ts
index 63f8eea091..0ce5524df8 100644
--- a/packages/legend-graph/src/graph-manager/protocol/pure/v1/transformation/pureGraph/to/V1_GraphBuilderContext.ts
+++ b/packages/legend-graph/src/graph-manager/protocol/pure/v1/transformation/pureGraph/to/V1_GraphBuilderContext.ts
@@ -35,7 +35,10 @@ import {
   ImportAwareCodeSection,
 } from '../../../../../../../graph/metamodel/pure/packageableElements/section/Section.js';
 import { StereotypeImplicitReference } from '../../../../../../../graph/metamodel/pure/packageableElements/domain/StereotypeReference.js';
-import { GenericTypeImplicitReference } from '../../../../../../../graph/metamodel/pure/packageableElements/domain/GenericTypeReference.js';
+import {
+  GenericTypeImplicitReference,
+  type GenericTypeReference,
+} from '../../../../../../../graph/metamodel/pure/packageableElements/domain/GenericTypeReference.js';
 import type { Type } from '../../../../../../../graph/metamodel/pure/packageableElements/domain/Type.js';
 import type { Class } from '../../../../../../../graph/metamodel/pure/packageableElements/domain/Class.js';
 import type { Enumeration } from '../../../../../../../graph/metamodel/pure/packageableElements/domain/Enumeration.js';
@@ -85,6 +88,7 @@ import {
   getOwnProperty,
   getStereotype,
   getTag,
+  newGenericType,
 } from '../../../../../../../graph/helpers/DomainHelper.js';
 import {
   getFilter,
@@ -96,6 +100,8 @@ import {
 } from '../../../../../../../graph/helpers/STO_FlatData_Helper.js';
 import type { PropertyOwner } from '../../../../../../../graph/metamodel/pure/packageableElements/domain/AbstractProperty.js';
 import type { DataElement } from '../../../../../../../graph/metamodel/pure/packageableElements/data/DataElement.js';
+import type { V1_GenericType } from '../../../model/packageableElements/type/V1_GenericType.js';
+import { V1_getGenericTypeFullPath } from '../../../helpers/V1_DomainHelper.js';
 
 export const V1_buildFullPath = (
   packagePath: string | undefined,
@@ -315,6 +321,19 @@ export class V1_GraphBuilderContext {
     return GenericTypeImplicitReference.create(ownerReference, value);
   };
 
+  resolveGenericTypeFromProtocol = (
+    genericType: V1_GenericType,
+  ): GenericTypeReference => {
+    const ownerReference = this.resolveType(
+      V1_getGenericTypeFullPath(genericType),
+    );
+    const typeArguments = genericType.typeArguments.map((g) =>
+      this.resolveGenericTypeFromProtocol(g),
+    );
+    const value = newGenericType(ownerReference.value, typeArguments);
+    return GenericTypeImplicitReference.create(ownerReference, value);
+  };
+
   resolveOwnProperty = (
     pointer: V1_PropertyPointer,
   ): PropertyImplicitReference => {
diff --git a/packages/legend-graph/src/graph-manager/protocol/pure/v1/transformation/pureGraph/to/V1_PropertyMappingBuilder.ts b/packages/legend-graph/src/graph-manager/protocol/pure/v1/transformation/pureGraph/to/V1_PropertyMappingBuilder.ts
index 9f1d799d42..5b9251e3c3 100644
--- a/packages/legend-graph/src/graph-manager/protocol/pure/v1/transformation/pureGraph/to/V1_PropertyMappingBuilder.ts
+++ b/packages/legend-graph/src/graph-manager/protocol/pure/v1/transformation/pureGraph/to/V1_PropertyMappingBuilder.ts
@@ -105,6 +105,9 @@ import { FlatDataAssociationPropertyMapping } from '../../../../../../../graph/m
 import type { V1_INTERNAL__UnknownPropertyMapping } from '../../../model/packageableElements/mapping/V1_INTERNAL__UnknownPropertyMapping.js';
 import { INTERNAL__UnknownPropertyMapping } from '../../../../../../../graph/metamodel/pure/packageableElements/mapping/INTERNAL__UnknownPropertyMapping.js';
 import { INTERNAL__PseudoMapping } from '../../../../../../../graph/metamodel/pure/packageableElements/mapping/INTERNAL__PseudoMapping.js';
+import type { V1_RelationFunctionPropertyMapping } from '../../../model/packageableElements/mapping/V1_RelationFunctionPropertyMapping.js';
+import { RelationFunctionPropertyMapping } from '../../../../../../../graph/metamodel/pure/packageableElements/mapping/relationFunction/RelationFunctionPropertyMapping.js';
+import { RelationColumn } from '../../../../../../../graph/metamodel/pure/packageableElements/relation/RelationType.js';
 
 const TEMPORARY__resolveSetImplementationByID = (
   mapping: Mapping,
@@ -1181,4 +1184,92 @@ export class V1_PropertyMappingBuilder
     }
     return aggregationAwarePropertyMapping;
   }
+
+  visit_RelationFunctionPropertyMapping(
+    protocol: V1_RelationFunctionPropertyMapping,
+  ): PropertyMapping {
+    assertNonNullable(
+      protocol.property,
+      `Relation Function property mapping 'property' field is missing`,
+    );
+    assertNonEmptyString(
+      protocol.property.property,
+      `Relation Function property mapping 'property.property' field is missing or empty`,
+    );
+    let propertyOwner: Class | Association;
+    let property: AbstractProperty;
+    let localMapping: LocalMappingPropertyInfo | undefined;
+    if (protocol.localMappingProperty) {
+      const localMappingProperty = protocol.localMappingProperty;
+      const mappingClass = new MappingClass(
+        `${this.topParent?._PARENT.path}_${this.topParent?.id}${protocol.property.property}`,
+      );
+      const _multiplicity = this.context.graph.getMultiplicity(
+        localMappingProperty.multiplicity.lowerBound,
+        localMappingProperty.multiplicity.upperBound,
+      );
+      const _property = new Property(
+        protocol.property.property,
+        _multiplicity,
+        this.context.resolveGenericType(localMappingProperty.type),
+        mappingClass,
+      );
+      property = PropertyImplicitReference.create(
+        PackageableElementImplicitReference.create(
+          mappingClass,
+          protocol.property.class,
+        ),
+        _property,
+      ).value;
+      localMapping = new LocalMappingPropertyInfo();
+      localMapping.localMappingProperty = true;
+      localMapping.localMappingPropertyMultiplicity = _multiplicity;
+      localMapping.localMappingPropertyType = this.context.resolveType(
+        localMappingProperty.type,
+      );
+      propertyOwner = property._OWNER;
+    } else {
+      if (protocol.property.class) {
+        propertyOwner = this.context.resolveClass(
+          protocol.property.class,
+        ).value;
+      } else {
+        throw new GraphBuilderError(
+          `Can't find property owner class for property '${protocol.property.property}'`,
+        );
+      }
+      property =
+        propertyOwner instanceof Class
+          ? getClassProperty(propertyOwner, protocol.property.property)
+          : getOwnProperty(propertyOwner, protocol.property.property);
+    }
+
+    const sourceSetImplementation = guaranteeNonNullable(
+      resolvePropertyMappingSourceImplementation(
+        this.immediateParent,
+        protocol,
+        this.topParent,
+        this.context,
+      ),
+    );
+    const propertyType = property.genericType.value.rawType;
+    const propertyMapping = new RelationFunctionPropertyMapping(
+      this.topParent ?? this.immediateParent,
+      PropertyImplicitReference.create(
+        PackageableElementImplicitReference.create(
+          propertyOwner,
+          protocol.property.class ?? '',
+        ),
+        property,
+      ),
+      SetImplementationImplicitReference.create(
+        sourceSetImplementation,
+        protocol.source,
+      ),
+      undefined,
+      new RelationColumn(protocol.column, propertyType),
+    );
+    propertyMapping.localMappingProperty = localMapping;
+    return propertyMapping;
+  }
 }
diff --git a/packages/legend-graph/src/graph-manager/protocol/pure/v1/transformation/pureGraph/to/helpers/V1_ValueSpecificationBuilderHelper.ts b/packages/legend-graph/src/graph-manager/protocol/pure/v1/transformation/pureGraph/to/helpers/V1_ValueSpecificationBuilderHelper.ts
index dce5dfb559..f83cf4be73 100644
--- a/packages/legend-graph/src/graph-manager/protocol/pure/v1/transformation/pureGraph/to/helpers/V1_ValueSpecificationBuilderHelper.ts
+++ b/packages/legend-graph/src/graph-manager/protocol/pure/v1/transformation/pureGraph/to/helpers/V1_ValueSpecificationBuilderHelper.ts
@@ -628,9 +628,7 @@ export const V1_buildBaseSimpleFunctionExpression = (
   expression.func = func;
   if (func) {
     const val = func.value;
-    expression.genericType = GenericTypeExplicitReference.create(
-      new GenericType(val.returnType.value),
-    );
+    expression.genericType = val.returnType;
     expression.multiplicity = val.returnMultiplicity;
   }
   expression.parametersValues = processedParameters;
diff --git a/packages/legend-graph/src/graph-manager/protocol/pure/v1/transformation/pureProtocol/serializationHelpers/V1_MappingSerializationHelper.ts b/packages/legend-graph/src/graph-manager/protocol/pure/v1/transformation/pureProtocol/serializationHelpers/V1_MappingSerializationHelper.ts
index bc2e98b048..485492b9ce 100644
--- a/packages/legend-graph/src/graph-manager/protocol/pure/v1/transformation/pureProtocol/serializationHelpers/V1_MappingSerializationHelper.ts
+++ b/packages/legend-graph/src/graph-manager/protocol/pure/v1/transformation/pureProtocol/serializationHelpers/V1_MappingSerializationHelper.ts
@@ -134,6 +134,8 @@ import { V1_MappingTest } from '../../../model/packageableElements/mapping/V1_Ma
 import type { V1_TestSuite } from '../../../model/test/V1_TestSuite.js';
 import { V1_INTERNAL__UnknownClassMapping } from '../../../model/packageableElements/mapping/V1_INTERNAL__UnknownClassMapping.js';
 import { V1_INTERNAL__UnknownMappingInclude } from '../../../model/packageableElements/mapping/V1_INTERNAL__UnknownMappingInclude.js';
+import { V1_RelationFunctionClassMapping } from '../../../model/packageableElements/mapping/V1_RelationFunctionClassMapping.js';
+import { V1_RelationFunctionPropertyMapping } from '../../../model/packageableElements/mapping/V1_RelationFunctionPropertyMapping.js';
 
 enum V1_ClassMappingType {
   OPERATION = 'operation',
@@ -143,6 +145,7 @@ enum V1_ClassMappingType {
   ROOT_RELATIONAL = 'relational',
   RELATIONAL = 'embedded',
   AGGREGATION_AWARE = 'aggregationAware',
+  RELATION_FUNCTION = 'relation',
 }
 
 enum V1_PropertyMappingType {
@@ -156,6 +159,7 @@ enum V1_PropertyMappingType {
   OTHERWISE_EMBEDDED_RELATIONAL = 'otherwiseEmbeddedPropertyMapping',
   AGGREGATION_AWARE = 'AggregationAwarePropertyMapping',
   XSTORE = 'xStorePropertyMapping',
+  RELATION_FUNCTION = 'relationFunctionPropertyMapping',
 }
 
 // ------------------------------------- Shared -------------------------------------
@@ -658,6 +662,57 @@ const aggregationAwareClassMappingModelSchema = (
     root: primitive(),
   });
 
+// ------------------------------------- Relation Function Mapping -------------------------------------
+
+const relationFunctionPropertyMappingModelSchema = createModelSchema(
+  V1_RelationFunctionPropertyMapping,
+  {
+    _type: usingConstantValueSchema(V1_PropertyMappingType.RELATION_FUNCTION),
+    localMappingProperty: usingModelSchema(
+      V1_localMappingPropertyInfoModelSchema,
+    ),
+    property: usingModelSchema(V1_propertyPointerModelSchema),
+    source: optional(primitive()),
+    target: optional(primitive()),
+    column: primitive(),
+  },
+);
+
+function V1_serializeRelationFunctionPropertyMapping(
+  protocol: V1_RelationFunctionPropertyMapping,
+): PlainObject<V1_RelationFunctionPropertyMapping> {
+  return serialize(relationFunctionPropertyMappingModelSchema, protocol);
+}
+
+function V1_deserializeRelationFunctionPropertyMapping(
+  json: PlainObject<V1_RelationFunctionPropertyMapping>,
+): V1_RelationFunctionPropertyMapping | typeof SKIP {
+  switch (json._type) {
+    case V1_PropertyMappingType.RELATION_FUNCTION:
+      return deserialize(relationFunctionPropertyMappingModelSchema, json);
+    default:
+      return SKIP;
+  }
+}
+
+const relationFunctionClassMappingModelSchema = createModelSchema(
+  V1_RelationFunctionClassMapping,
+  {
+    _type: usingConstantValueSchema(V1_ClassMappingType.RELATION_FUNCTION),
+    class: primitive(),
+    extendsClassMappingId: optional(primitive()),
+    id: optional(primitive()),
+    propertyMappings: list(
+      custom(
+        V1_serializeRelationFunctionPropertyMapping,
+        V1_deserializeRelationFunctionPropertyMapping,
+      ),
+    ),
+    root: primitive(),
+    relationFunction: usingModelSchema(V1_packageableElementPointerModelSchema),
+  },
+);
+
 // ------------------------------------- Class Mapping -------------------------------------
 
 function V1_serializeClassMapping(
@@ -680,6 +735,8 @@ function V1_serializeClassMapping(
     return serialize(relationalClassMappingModelSchema, value);
   } else if (value instanceof V1_AggregationAwareClassMapping) {
     return serialize(aggregationAwareClassMappingModelSchema(plugins), value);
+  } else if (value instanceof V1_RelationFunctionClassMapping) {
+    return serialize(relationFunctionClassMappingModelSchema, value);
   }
   const extraClassMappingSerializers = plugins.flatMap(
     (plugin) =>
@@ -730,6 +787,8 @@ function V1_deserializeClassMapping(
         aggregationAwareClassMappingModelSchema(plugins),
         json,
       );
+    case V1_ClassMappingType.RELATION_FUNCTION:
+      return deserialize(relationFunctionClassMappingModelSchema, json);
     default: {
       const extraClassMappingDeserializers = plugins.flatMap(
         (plugin) =>
diff --git a/packages/legend-graph/src/graph/Core_HashUtils.ts b/packages/legend-graph/src/graph/Core_HashUtils.ts
index eb2e0cb9b2..41ababf5a9 100644
--- a/packages/legend-graph/src/graph/Core_HashUtils.ts
+++ b/packages/legend-graph/src/graph/Core_HashUtils.ts
@@ -290,6 +290,8 @@ export enum CORE_HASH_STRUCTURE {
   EMBEDDED_REALTIONAL_PROPERTY_MAPPING = 'EMBEDDED_REALTIONAL_PROPERTY_MAPPING',
   INLINE_EMBEDDED_REALTIONAL_PROPERTY_MAPPING = 'INLINE_EMBEDDED_REALTIONAL_PROPERTY_MAPPING',
   OTHERWISE_EMBEDDED_REALTIONAL_PROPERTY_MAPPING = 'OTHERWISE_EMBEDDED_REALTIONAL_PROPERTY_MAPPING',
+  RELATION_FUNCTION_INSTANCE_SET_IMPLEMENTATION = 'RELATION_FUNCTION_INSTANCE_SET_IMPLEMENTATION',
+  RELATION_FUNCTION_PROPERTY_MAPPING = 'RELATION_FUNCTION_PROPERTY_MAPPING',
 
   // milestoning
   BUSINESS_MILESTONING = 'BUSINESS_MILESTONING',
diff --git a/packages/legend-graph/src/graph/helpers/DomainHelper.ts b/packages/legend-graph/src/graph/helpers/DomainHelper.ts
index f162cc292d..44cc58b567 100644
--- a/packages/legend-graph/src/graph/helpers/DomainHelper.ts
+++ b/packages/legend-graph/src/graph/helpers/DomainHelper.ts
@@ -64,7 +64,7 @@ import type {
 import { DerivedProperty } from '../metamodel/pure/packageableElements/domain/DerivedProperty.js';
 import type { Enum } from '../metamodel/pure/packageableElements/domain/Enum.js';
 import type { Constraint } from '../metamodel/pure/packageableElements/domain/Constraint.js';
-import type { GenericType } from '../metamodel/pure/packageableElements/domain/GenericType.js';
+import { GenericType } from '../metamodel/pure/packageableElements/domain/GenericType.js';
 import { Multiplicity } from '../metamodel/pure/packageableElements/domain/Multiplicity.js';
 import type { AnnotatedElement } from '../metamodel/pure/packageableElements/domain/AnnotatedElement.js';
 import type { ConcreteFunctionDefinition } from '../metamodel/pure/packageableElements/function/ConcreteFunctionDefinition.js';
@@ -74,6 +74,7 @@ import {
   FunctionAnalysisParameterInfo,
 } from './FunctionAnalysis.js';
 import { generateFunctionPrettyName } from './PureLanguageHelper.js';
+import type { GenericTypeReference } from '../metamodel/pure/packageableElements/domain/GenericTypeReference.js';
 
 export const addElementToPackage = (
   parent: Package,
@@ -731,7 +732,7 @@ export const getFunctionSignature = (
           p.multiplicity.upperBound,
         )}_`,
     )
-    .join('_')}_${func.returnType.value.name}_${getMultiplicityString(
+    .join('_')}_${func.returnType.value.rawType.name}_${getMultiplicityString(
     func.returnMultiplicity.lowerBound,
     func.returnMultiplicity.upperBound,
   )}_`;
@@ -759,7 +760,7 @@ export const buildFunctionAnalysisInfoFromConcreteFunctionDefinition = (
       spacing: false,
     });
     functionInfo.packagePath = func.package?.path ?? '';
-    functionInfo.returnType = func.returnType.value.name;
+    functionInfo.returnType = func.returnType.value.rawType.name;
     functionInfo.parameterInfoList = func.parameters.map((param) => {
       const paramInfo = new FunctionAnalysisParameterInfo();
       paramInfo.multiplicity = graph.getMultiplicity(
@@ -832,3 +833,12 @@ export const getElementOrigin = (
   }
   return '';
 };
+
+export const newGenericType = (
+  rawType: Type,
+  typeArguments: GenericTypeReference[],
+): GenericType => {
+  const genericType = new GenericType(rawType);
+  genericType.typeArguments = typeArguments;
+  return genericType;
+};
diff --git a/packages/legend-graph/src/graph/helpers/PureLanguageHelper.ts b/packages/legend-graph/src/graph/helpers/PureLanguageHelper.ts
index 9ab7a338c0..74d7fbe67b 100644
--- a/packages/legend-graph/src/graph/helpers/PureLanguageHelper.ts
+++ b/packages/legend-graph/src/graph/helpers/PureLanguageHelper.ts
@@ -28,6 +28,7 @@ import { Enumeration } from '../metamodel/pure/packageableElements/domain/Enumer
 import { formatDate } from '@finos/legend-shared';
 import type { PureModel } from '../PureModel.js';
 import type { FunctionAnalysisInfo } from './FunctionAnalysis.js';
+import type { GenericType } from '../metamodel/pure/packageableElements/domain/GenericType.js';
 
 export enum PURE_ELEMENT_NAME {
   PROFILE = 'Profile',
@@ -165,6 +166,15 @@ export const generateFunctionCallStringFromFunctionAnalysisInfo = (
   return `${functionInfo.packagePath}${ELEMENT_PATH_DELIMITER}${functionInfo.functionName}(${lambdaString})`;
 };
 
+export const generateGenericTypeString = (type: GenericType): string => {
+  return (
+    type.rawType.name +
+    (type.typeArguments?.length
+      ? `<${type.typeArguments.map((t) => generateGenericTypeString(t.value)).join(', ')}>`
+      : '')
+  );
+};
+
 export const generateFunctionPrettyName = (
   element: ConcreteFunctionDefinition,
   options?: {
@@ -187,9 +197,9 @@ export const generateFunctionPrettyName = (
             p.multiplicity.upperBound,
           )}]`,
     )
-    .join(', ')}): ${
-    element.returnType.value.name
-  }[${generateMultiplicityString(
+    .join(', ')}): ${generateGenericTypeString(
+    element.returnType.value,
+  )}[${generateMultiplicityString(
     element.returnMultiplicity.lowerBound,
     element.returnMultiplicity.upperBound,
   )}]`.replaceAll(/\s*/gu, (val) => {
diff --git a/packages/legend-graph/src/graph/helpers/__tests__/PureLanguageHelper.test.ts b/packages/legend-graph/src/graph/helpers/__tests__/PureLanguageHelper.test.ts
index 5a5f1f9907..d18f37d56d 100644
--- a/packages/legend-graph/src/graph/helpers/__tests__/PureLanguageHelper.test.ts
+++ b/packages/legend-graph/src/graph/helpers/__tests__/PureLanguageHelper.test.ts
@@ -23,6 +23,7 @@ import {
   generateFunctionPrettyName,
 } from '../PureLanguageHelper.js';
 import { TEST__getTestGraph } from '../../__test-utils__/GraphTestUtils.js';
+import { getFunctionSignature } from '../DomainHelper.js';
 
 afterEach(() => {
   // running all pending timers and switching to real timers using Jest
@@ -50,4 +51,18 @@ test(unitTest('Generate default parameter value for type'), async () => {
   ).toBe(
     'model::functions::set(name: String[1], type: IncType[1], date: Date[1], dateTime: DateTime[1]): String[1]',
   );
+  expect(getFunctionSignature(setFunction)).toBe(
+    '_String_1__IncType_1__Date_1__DateTime_1__String_1_',
+  );
+
+  const relationFunction = graph.getFunction(
+    'model::functions::relationFunction__Relation_$0_1$_',
+  );
+  expect(
+    generateFunctionPrettyName(relationFunction, {
+      fullPath: true,
+      spacing: true,
+    }),
+  ).toBe('model::functions::relationFunction(): Relation<Any>[0..1]');
+  expect(getFunctionSignature(relationFunction)).toBe('__Relation_$0_1$_');
 });
diff --git a/packages/legend-graph/src/graph/helpers/__tests__/TEST_DATA__FunctionSignatureGeneration.json b/packages/legend-graph/src/graph/helpers/__tests__/TEST_DATA__FunctionSignatureGeneration.json
index ec427970a9..3a62640407 100644
--- a/packages/legend-graph/src/graph/helpers/__tests__/TEST_DATA__FunctionSignatureGeneration.json
+++ b/packages/legend-graph/src/graph/helpers/__tests__/TEST_DATA__FunctionSignatureGeneration.json
@@ -158,6 +158,46 @@
     },
     "classifierPath": "meta::pure::metamodel::function::ConcreteFunctionDefinition"
   },
+  {
+    "path": "model::functions::relationFunction",
+    "content": {
+      "_type": "function",
+      "body": [
+        {
+          "_type": "collection",
+          "multiplicity": {
+            "lowerBound": 0,
+            "upperBound": 0
+          },
+          "values": []
+        }
+      ],
+      "name": "relationFunction__Relation_$0_1$_",
+      "package": "model::functions",
+      "parameters": [],
+      "postConstraints": [],
+      "preConstraints": [],
+      "returnGenericType": {
+        "rawType": {
+          "_type": "packageableType",
+          "fullPath": "meta::pure::metamodel::relation::Relation"
+        },
+        "typeArguments": [
+          {
+            "rawType": {
+              "_type": "packageableType",
+              "fullPath": "Any"
+            }
+          }
+        ]
+      },
+      "returnMultiplicity": {
+        "lowerBound": 0,
+        "upperBound": 1
+      }
+    },
+    "classifierPath": "meta::pure::metamodel::function::ConcreteFunctionDefinition"
+  },
   {
     "path": "model::Test",
     "content": {
diff --git a/packages/legend-graph/src/graph/metamodel/pure/packageableElements/function/ConcreteFunctionDefinition.ts b/packages/legend-graph/src/graph/metamodel/pure/packageableElements/function/ConcreteFunctionDefinition.ts
index c27b2fcab4..e9e48dea30 100644
--- a/packages/legend-graph/src/graph/metamodel/pure/packageableElements/function/ConcreteFunctionDefinition.ts
+++ b/packages/legend-graph/src/graph/metamodel/pure/packageableElements/function/ConcreteFunctionDefinition.ts
@@ -21,18 +21,17 @@ import {
 } from '../../../../Core_HashUtils.js';
 import type { PackageableElementVisitor } from '../PackageableElement.js';
 import type { RawVariableExpression } from '../../rawValueSpecification/RawVariableExpression.js';
-import type { Type } from '../domain/Type.js';
 import type { Multiplicity } from '../domain/Multiplicity.js';
-import type { PackageableElementReference } from '../PackageableElementReference.js';
 import { FunctionDefinition } from '../domain/Function.js';
 import type { Testable } from '../../test/Testable.js';
 import type { FunctionTestSuite } from './test/FunctionTestSuite.js';
+import type { GenericTypeReference } from '../domain/GenericTypeReference.js';
 
 export class ConcreteFunctionDefinition
   extends FunctionDefinition
   implements Hashable, Testable
 {
-  returnType: PackageableElementReference<Type>;
+  returnType: GenericTypeReference;
   returnMultiplicity: Multiplicity;
   /**
    * Studio does not process value specification, they are left in raw JSON form
@@ -50,7 +49,7 @@ export class ConcreteFunctionDefinition
 
   constructor(
     name: string,
-    returnType: PackageableElementReference<Type>,
+    returnType: GenericTypeReference,
     returnMultiplicity: Multiplicity,
   ) {
     super(name);
@@ -63,7 +62,7 @@ export class ConcreteFunctionDefinition
       CORE_HASH_STRUCTURE.FUNCTION,
       this.path,
       hashArray(this.parameters),
-      this.returnType.valueForSerialization ?? '',
+      this.returnType.ownerReference.valueForSerialization ?? '',
       hashArray(this.taggedValues),
       hashArray(this.stereotypes.map((val) => val.pointerHashCode)),
       hashRawLambda(undefined, this.expressionSequence),
diff --git a/packages/legend-graph/src/graph/metamodel/pure/packageableElements/mapping/PropertyMapping.ts b/packages/legend-graph/src/graph/metamodel/pure/packageableElements/mapping/PropertyMapping.ts
index de21b0831e..0105d104e4 100644
--- a/packages/legend-graph/src/graph/metamodel/pure/packageableElements/mapping/PropertyMapping.ts
+++ b/packages/legend-graph/src/graph/metamodel/pure/packageableElements/mapping/PropertyMapping.ts
@@ -31,6 +31,7 @@ import type { XStorePropertyMapping } from './xStore/XStorePropertyMapping.js';
 import type { LocalMappingPropertyInfo } from './LocalMappingPropertyInfo.js';
 import type { SetImplementationReference } from './SetImplementationReference.js';
 import type { INTERNAL__UnknownPropertyMapping } from './INTERNAL__UnknownPropertyMapping.js';
+import type { RelationFunctionPropertyMapping } from './relationFunction/RelationFunctionPropertyMapping.js';
 
 export interface PropertyMappingVisitor<T> {
   visit_PropertyMapping(propertyMapping: PropertyMapping): T;
@@ -62,6 +63,9 @@ export interface PropertyMappingVisitor<T> {
     propertyMapping: AggregationAwarePropertyMapping,
   ): T;
   visit_XStorePropertyMapping(propertyMapping: XStorePropertyMapping): T;
+  visit_RelationFunctionPropertyMapping(
+    propertyMapping: RelationFunctionPropertyMapping,
+  ): T;
 }
 
 export abstract class PropertyMapping implements Hashable {
diff --git a/packages/legend-graph/src/graph/metamodel/pure/packageableElements/mapping/SetImplementation.ts b/packages/legend-graph/src/graph/metamodel/pure/packageableElements/mapping/SetImplementation.ts
index c1a4b5c442..0e674267b2 100644
--- a/packages/legend-graph/src/graph/metamodel/pure/packageableElements/mapping/SetImplementation.ts
+++ b/packages/legend-graph/src/graph/metamodel/pure/packageableElements/mapping/SetImplementation.ts
@@ -15,7 +15,7 @@
  */
 
 import { hashArray, type Hashable } from '@finos/legend-shared';
-import { CORE_HASH_STRUCTURE } from '../../../../../graph/Core_HashUtils.js';
+import { CORE_HASH_STRUCTURE } from '../../../../Core_HashUtils.js';
 import type { PackageableElementReference } from '../PackageableElementReference.js';
 import type { PropertyOwnerImplementation } from './PropertyOwnerImplementation.js';
 import type { Mapping } from './Mapping.js';
@@ -33,6 +33,7 @@ import type { MergeOperationSetImplementation } from './MergeOperationSetImpleme
 import type { INTERNAL__UnresolvedSetImplementation } from './INTERNAL__UnresolvedSetImplementation.js';
 import type { Class } from '../domain/Class.js';
 import type { INTERNAL__UnknownSetImplementation } from './INTERNAL__UnknownSetImplementation.js';
+import type { RelationFunctionInstanceSetImplementation } from './relationFunction/RelationFunctionInstanceSetImplementation.js';
 
 export interface SetImplementationVisitor<T> {
   visit_SetImplementation(setImplementation: InstanceSetImplementation): T;
@@ -68,6 +69,9 @@ export interface SetImplementationVisitor<T> {
   visit_AggregationAwareSetImplementation(
     setImplementation: AggregationAwareSetImplementation,
   ): T;
+  visit_RelationFunctionInstanceSetImplementation(
+    setImplementation: RelationFunctionInstanceSetImplementation,
+  ): T;
 }
 
 export abstract class SetImplementation
diff --git a/packages/legend-graph/src/graph/metamodel/pure/packageableElements/mapping/relationFunction/RelationFunctionInstanceSetImplementation.ts b/packages/legend-graph/src/graph/metamodel/pure/packageableElements/mapping/relationFunction/RelationFunctionInstanceSetImplementation.ts
new file mode 100644
index 0000000000..2a122f24eb
--- /dev/null
+++ b/packages/legend-graph/src/graph/metamodel/pure/packageableElements/mapping/relationFunction/RelationFunctionInstanceSetImplementation.ts
@@ -0,0 +1,58 @@
+/**
+ * Copyright (c) 2020-present, Goldman Sachs
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * Copyright (c) 2025-present, Goldman Sachs
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { type Hashable, hashArray } from '@finos/legend-shared';
+import { CORE_HASH_STRUCTURE } from '../../../../../Core_HashUtils.js';
+import type { SetImplementationVisitor } from '../SetImplementation.js';
+import type { ConcreteFunctionDefinition } from '../../function/ConcreteFunctionDefinition.js';
+import { InstanceSetImplementation } from '../InstanceSetImplementation.js';
+
+export class RelationFunctionInstanceSetImplementation
+  extends InstanceSetImplementation
+  implements Hashable
+{
+  relationFunction?: ConcreteFunctionDefinition;
+
+  override accept_SetImplementationVisitor<T>(
+    visitor: SetImplementationVisitor<T>,
+  ): T {
+    return visitor.visit_RelationFunctionInstanceSetImplementation(this);
+  }
+
+  override get hashCode(): string {
+    return hashArray([
+      CORE_HASH_STRUCTURE.RELATION_FUNCTION_INSTANCE_SET_IMPLEMENTATION,
+      super.hashCode,
+      hashArray(this.propertyMappings),
+    ]);
+  }
+}
diff --git a/packages/legend-graph/src/graph/metamodel/pure/packageableElements/mapping/relationFunction/RelationFunctionPropertyMapping.ts b/packages/legend-graph/src/graph/metamodel/pure/packageableElements/mapping/relationFunction/RelationFunctionPropertyMapping.ts
new file mode 100644
index 0000000000..1d3d6ff54a
--- /dev/null
+++ b/packages/legend-graph/src/graph/metamodel/pure/packageableElements/mapping/relationFunction/RelationFunctionPropertyMapping.ts
@@ -0,0 +1,72 @@
+/**
+ * Copyright (c) 2020-present, Goldman Sachs
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * Copyright (c) 2025-present, Goldman Sachs
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { CORE_HASH_STRUCTURE } from '../../../../../Core_HashUtils.js';
+import { hashArray, type Hashable } from '@finos/legend-shared';
+import {
+  type PropertyMappingVisitor,
+  PropertyMapping,
+} from '../PropertyMapping.js';
+import type { PropertyReference } from '../../domain/PropertyReference.js';
+import type { PropertyMappingsImplementation } from '../PropertyMappingsImplementation.js';
+import type { SetImplementationReference } from '../SetImplementationReference.js';
+import type { RelationColumn } from '../../relation/RelationType.js';
+
+export class RelationFunctionPropertyMapping
+  extends PropertyMapping
+  implements Hashable
+{
+  column: RelationColumn;
+
+  constructor(
+    owner: PropertyMappingsImplementation,
+    property: PropertyReference,
+    source: SetImplementationReference,
+    target: SetImplementationReference | undefined,
+    column: RelationColumn,
+  ) {
+    super(owner, property, source, target);
+    this.column = column;
+  }
+
+  override get hashCode(): string {
+    return hashArray([
+      CORE_HASH_STRUCTURE.RELATION_FUNCTION_PROPERTY_MAPPING,
+      super.hashCode,
+      this.column.name,
+    ]);
+  }
+
+  accept_PropertyMappingVisitor<T>(visitor: PropertyMappingVisitor<T>): T {
+    return visitor.visit_RelationFunctionPropertyMapping(this);
+  }
+}
diff --git a/packages/legend-graph/src/index.ts b/packages/legend-graph/src/index.ts
index bd0189b219..3bd1f5034d 100644
--- a/packages/legend-graph/src/index.ts
+++ b/packages/legend-graph/src/index.ts
@@ -645,6 +645,7 @@ export * from './graph/metamodel/pure/packageableElements/mapping/EnumValueMappi
 export { AssociationImplementation } from './graph/metamodel/pure/packageableElements/mapping/AssociationImplementation.js';
 export { SetImplementationContainer } from './graph/metamodel/pure/packageableElements/mapping/SetImplementationContainer.js';
 export { AggregationAwareSetImplementation } from './graph/metamodel/pure/packageableElements/mapping/aggregationAware/AggregationAwareSetImplementation.js';
+export { RelationFunctionInstanceSetImplementation } from './graph/metamodel/pure/packageableElements/mapping/relationFunction/RelationFunctionInstanceSetImplementation.js';
 export * from './graph/metamodel/pure/packageableElements/mapping/InferableMappingElementId.js';
 export * from './graph/metamodel/pure/packageableElements/mapping/InferableMappingElementRoot.js';
 export { SetImplementationExplicitReference } from './graph/metamodel/pure/packageableElements/mapping/SetImplementationReference.js';
diff --git a/packages/legend-manual-tests/src/__tests__/roundtrip-grammar/cases/STO_Relational-relation-function-mapping.pure b/packages/legend-manual-tests/src/__tests__/roundtrip-grammar/cases/STO_Relational-relation-function-mapping.pure
new file mode 100644
index 0000000000..e5a7c2d973
--- /dev/null
+++ b/packages/legend-manual-tests/src/__tests__/roundtrip-grammar/cases/STO_Relational-relation-function-mapping.pure
@@ -0,0 +1,99 @@
+###Relational
+Database my::testDB
+(
+  Table personTable
+  (
+    ID INTEGER PRIMARY KEY,
+    FIRSTNAME VARCHAR(100),
+    AGE INTEGER,
+    FIRMID INTEGER
+  )
+  Table firmTable
+  (
+    ID INTEGER PRIMARY KEY,
+    LEGALNAME VARCHAR(100)
+  )
+)
+
+
+###Pure
+Class my::Firm
+{
+  legalName: String[1];
+}
+
+Class my::Person
+{
+  firstName: String[1];
+  age: Integer[1];
+}
+
+Association my::Person_Firm
+{
+  employees: my::Person[*];
+  firm: my::Firm[1];
+}
+
+function my::firmFunction(): meta::pure::metamodel::relation::Relation<meta::pure::metamodel::type::Any>[1]
+{
+  #>{my::testDB.firmTable}#->limit(10)->select(~[ID, LEGALNAME])
+}
+
+function my::personFunction(): meta::pure::metamodel::relation::Relation<meta::pure::metamodel::type::Any>[1]
+{
+  #>{my::testDB.personTable}#->filter(x|$x.AGE > 25)->limit(5)
+}
+
+
+###Mapping
+Mapping my::relationFunctionMapping
+(
+  *my::Person[person]: Relation
+  {
+    ~func my::personFunction():Relation<Any>[1]
+    firstName: FIRSTNAME,
+    age: AGE,
+    +firmId: Integer[1]: FIRMID
+  }
+  *my::Firm[firm]: Relation
+  {
+    ~func my::firmFunction():Relation<Any>[1]
+    legalName: LEGALNAME,
+    +id: Integer[1]: ID
+  }
+
+  my::Person_Firm: XStore
+  {
+    employees[firm, person]: $this.id == $that.firmId,
+    firm[person, firm]: $this.firmId == $that.id
+  }
+)
+
+
+###Connection
+RelationalDatabaseConnection my::conn
+{
+  store: my::testDB;
+  type: H2;
+  specification: LocalH2
+  {
+  };
+  auth: DefaultH2;
+}
+
+
+###Runtime
+Runtime my::runtime
+{
+  mappings:
+  [
+    my::relationFunctionMapping
+  ];
+  connections:
+  [
+    my::testDB:
+    [
+      connection_1: my::conn
+    ]
+  ];
+}
diff --git a/packages/legend-manual-tests/src/__tests__/roundtrip-grammar/cases/STO_Relational-relational-and-relation-function-mapping.pure b/packages/legend-manual-tests/src/__tests__/roundtrip-grammar/cases/STO_Relational-relational-and-relation-function-mapping.pure
new file mode 100644
index 0000000000..73b0335c99
--- /dev/null
+++ b/packages/legend-manual-tests/src/__tests__/roundtrip-grammar/cases/STO_Relational-relational-and-relation-function-mapping.pure
@@ -0,0 +1,103 @@
+###Relational
+Database my::testDB
+(
+  Table personTable
+  (
+    ID INTEGER PRIMARY KEY,
+    FIRSTNAME VARCHAR(100),
+    AGE INTEGER,
+    FIRMID INTEGER
+  )
+  Table firmTable
+  (
+    ID INTEGER PRIMARY KEY,
+    LEGALNAME VARCHAR(100)
+  )
+)
+
+
+###Pure
+Class my::Firm
+{
+  legalName: String[1];
+}
+
+Class my::Person
+{
+  firstName: String[1];
+  age: Integer[1];
+}
+
+Association my::Person_Firm
+{
+  employees: my::Person[*];
+  firm: my::Firm[1];
+}
+
+function my::firmFunction(): meta::pure::metamodel::relation::Relation<meta::pure::metamodel::type::Any>[1]
+{
+  #>{my::testDB.firmTable}#->limit(10)->select(~[ID, LEGALNAME])
+}
+
+function my::personFunction(): meta::pure::metamodel::relation::Relation<meta::pure::metamodel::type::Any>[1]
+{
+  #>{my::testDB.personTable}#->filter(x|$x.AGE > 25)->limit(5)
+}
+
+
+###Mapping
+Mapping my::relationFunctionMapping
+(
+  *my::Person[person]: Relation
+  {
+    ~func my::personFunction():Relation<Any>[1]
+    firstName: FIRSTNAME,
+    age: AGE,
+    +firmId: Integer[1]: FIRMID
+  }
+  *my::Firm[firm]: Relational
+  {
+    ~primaryKey
+    (
+      [my::testDB]firmTable.ID
+    )
+    ~mainTable [my::testDB]firmTable
+    +id: Integer[1]: [my::testDB]firmTable.ID,
+    legalName: [my::testDB]firmTable.LEGALNAME
+  }
+
+  my::Person_Firm: XStore
+  {
+    employees[firm, person]: $this.id == $that.firmId,
+    firm[person, firm]: $this.firmId == $that.id
+  }
+)
+
+
+###Connection
+RelationalDatabaseConnection my::conn
+{
+  store: my::testDB;
+  type: H2;
+  specification: LocalH2
+  {
+  };
+  auth: DefaultH2;
+}
+
+
+###Runtime
+Runtime my::runtime
+{
+  mappings:
+  [
+    my::relationFunctionMapping
+  ];
+  connections:
+  [
+    my::testDB:
+    [
+      connection_1: my::conn
+    ]
+  ];
+}