diff --git a/src/System.Windows.Forms.Design/tests/UnitTests/System/Windows/Forms/Design/DesignerFrameTests.cs b/src/System.Windows.Forms.Design/tests/UnitTests/System/Windows/Forms/Design/DesignerFrameTests.cs
new file mode 100644
index 00000000000..02f860b74c4
--- /dev/null
+++ b/src/System.Windows.Forms.Design/tests/UnitTests/System/Windows/Forms/Design/DesignerFrameTests.cs
@@ -0,0 +1,171 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+#nullable enable
+
+using System.ComponentModel;
+using System.Drawing;
+using Moq;
+
+namespace System.Windows.Forms.Design.Tests;
+
+public class DesignerFrameTests
+{
+    private readonly Mock<ISite> _mockSite = new();
+
+    private class TestDesignerFrame : DesignerFrame
+    {
+        public TestDesignerFrame(ISite site) : base(site) { }
+
+        public void TestSetSite(ISite site)
+        {
+            Site = site;
+        }
+
+        public new bool ProcessDialogKey(Keys keyData)
+        {
+            return base.ProcessDialogKey(keyData);
+        }
+    }
+
+    private void SetupMocks()
+    {
+        Mock<IUIService> mockUIService = new();
+        mockUIService.Setup(ui => ui.Styles["ArtboardBackground"]).Returns(Color.Red);
+        _mockSite.Setup(site => site.GetService(typeof(IUIService))).Returns(mockUIService.Object);
+    }
+
+    [Fact]
+    public void DesignerFrame_Constructor_SetsTextBackColorAndControls()
+    {
+        SetupMocks();
+
+        DesignerFrame designerFrame = new(_mockSite.Object);
+        try
+        {
+            designerFrame.Text.Should().Be("DesignerFrame");
+            designerFrame.BackColor.Should().Be(Color.Red);
+
+            designerFrame.Controls.Cast<Control>().Should().HaveCount(1);
+        }
+        finally
+        {
+            designerFrame.Dispose();
+        }
+    }
+
+    [Fact]
+    public void DesignerFrame_Initialize_SetsDesignerProperties()
+    {
+        Control control = new();
+        DesignerFrame designerFrame = new(_mockSite.Object);
+        try
+        {
+            designerFrame.Initialize(control);
+
+            List<Control> controls = designerFrame.Controls.Cast<Control>().ToList();
+            Control? designerRegion = controls.FirstOrDefault(c => c is ScrollableControl);
+
+            designerRegion.Should().NotBeNull();
+
+            Control? containedControl = designerRegion?.Controls.Cast<Control>().FirstOrDefault();
+            containedControl.Should().Be(control);
+
+            control.Visible.Should().BeTrue();
+            control.Enabled.Should().BeTrue();
+
+            designerFrame.Controls.Cast<Control>().Should().NotContain(control);
+        }
+        finally
+        {
+            control.Dispose();
+            designerFrame.Dispose();
+        }
+    }
+
+    [Fact]
+    public void DesignerFrame_ProcessDialogKey_ReturnsExpectedResult()
+    {
+        TestDesignerFrame designerFrame = new(_mockSite.Object);
+        try
+        {
+            bool result = designerFrame.ProcessDialogKey(Keys.Enter);
+
+            result.Should().BeFalse();
+        }
+        finally
+        {
+            designerFrame.Dispose();
+        }
+    }
+
+    [Fact]
+    public void DesignerFrame_Constructor_SetsSitePropertyUsingTestSetSite()
+    {
+        TestDesignerFrame designerFrame = new(_mockSite.Object);
+        try
+        {
+            designerFrame.TestSetSite(_mockSite.Object);
+
+            designerFrame.Site.Should().Be(_mockSite.Object);
+        }
+        finally
+        {
+            designerFrame.Dispose();
+        }
+    }
+
+    [Fact]
+    public void DesignerFrame_AddControl_AddsControlToFrame()
+    {
+        Control control = new();
+        DesignerFrame designerFrame = new(_mockSite.Object);
+        try
+        {
+            designerFrame.Controls.Add(control);
+
+            designerFrame.Controls.Cast<Control>().Should().Contain(control);
+        }
+        finally
+        {
+            control.Dispose();
+            designerFrame.Dispose();
+        }
+    }
+
+    [Fact]
+    public void DesignerFrame_Resize_TriggersExpectedBehavior()
+    {
+        DesignerFrame designerFrame = new(_mockSite.Object);
+        bool resizeEventTriggered = false;
+
+        try
+        {
+            designerFrame.Resize += (sender, args) => resizeEventTriggered = true;
+            designerFrame.Width = 500;
+
+            resizeEventTriggered.Should().BeTrue();
+            designerFrame.Width.Should().Be(500);
+        }
+        finally
+        {
+            designerFrame.Dispose();
+        }
+    }
+
+    [Fact]
+    public void Designer_ProcessDialogKey()
+    {
+        TestDesignerFrame designerFrame = new(_mockSite.Object);
+        try
+        {
+            bool result = designerFrame.ProcessDialogKey(Keys.Enter);
+
+            result.Should().BeFalse();
+        }
+        finally
+        {
+            designerFrame.Dispose();
+        }
+    }
+}