diff --git a/README.md b/README.md
index 61b803c4c..c88c49287 100644
--- a/README.md
+++ b/README.md
@@ -139,6 +139,19 @@ import {GoogleGenAI} from '@google/genai';
 const ai = new GoogleGenAI();
 ```
 
+### Mutual TLS (mTLS) Authentication
+
+For Node.js environments requiring mTLS authentication, you can configure client certificates using environment variables:
+
+**Setting up mTLS with environment variables:**
+
+```bash
+export GOOGLE_CLIENT_CERT='/path/to/client-cert.pem'
+export GOOGLE_CLIENT_KEY='/path/to/client-key.pem'
+```
+
+Alternatively, you can use `GEMINI_CLIENT_CERT` and `GEMINI_CLIENT_KEY`. 
+
 ## API Selection
 
 By default, the SDK uses the beta API endpoints provided by Google to support
diff --git a/api-report/genai-node.api.md b/api-report/genai-node.api.md
index f36ca11a8..2d537c7c2 100644
--- a/api-report/genai-node.api.md
+++ b/api-report/genai-node.api.md
@@ -1801,6 +1801,7 @@ export enum HttpElementLocation {
 export interface HttpOptions {
     apiVersion?: string;
     baseUrl?: string;
+    dispatcher?: unknown;
     extraBody?: Record<string, unknown>;
     headers?: Record<string, string>;
     timeout?: number;
diff --git a/api-report/genai-web.api.md b/api-report/genai-web.api.md
index f36ca11a8..2d537c7c2 100644
--- a/api-report/genai-web.api.md
+++ b/api-report/genai-web.api.md
@@ -1801,6 +1801,7 @@ export enum HttpElementLocation {
 export interface HttpOptions {
     apiVersion?: string;
     baseUrl?: string;
+    dispatcher?: unknown;
     extraBody?: Record<string, unknown>;
     headers?: Record<string, string>;
     timeout?: number;
diff --git a/api-report/genai.api.md b/api-report/genai.api.md
index f36ca11a8..2d537c7c2 100644
--- a/api-report/genai.api.md
+++ b/api-report/genai.api.md
@@ -1801,6 +1801,7 @@ export enum HttpElementLocation {
 export interface HttpOptions {
     apiVersion?: string;
     baseUrl?: string;
+    dispatcher?: unknown;
     extraBody?: Record<string, unknown>;
     headers?: Record<string, string>;
     timeout?: number;
diff --git a/package.json b/package.json
index 7482aa3bb..dfee06bd8 100644
--- a/package.json
+++ b/package.json
@@ -108,13 +108,13 @@
     "typedoc": "^0.27.0",
     "typescript": "~5.2.0",
     "typescript-eslint": "8.24.1",
-    "undici": "^7.16.0",
     "undici-types": "^7.16.0",
     "zod": "^3.22.4",
     "zod-to-json-schema": "^3.22.4"
   },
   "dependencies": {
     "google-auth-library": "^10.3.0",
+    "undici": "^7.16.0",
     "ws": "^8.18.0"
   },
   "peerDependencies": {
diff --git a/src/_api_client.ts b/src/_api_client.ts
index 9a33e0b4c..2d84a4ef0 100644
--- a/src/_api_client.ts
+++ b/src/_api_client.ts
@@ -382,13 +382,17 @@ export class ApiClient {
     baseHttpOptions: types.HttpOptions,
     requestHttpOptions: types.HttpOptions,
   ): types.HttpOptions {
-    const patchedHttpOptions = JSON.parse(
-      JSON.stringify(baseHttpOptions),
-    ) as types.HttpOptions;
+    // Shallow clone to preserve non-serializable fields like dispatcher
+    const patchedHttpOptions: types.HttpOptions = {...baseHttpOptions};
 
     for (const [key, value] of Object.entries(requestHttpOptions)) {
+      // Skip dispatcher if it's being patched from baseHttpOptions
+      if (key === 'dispatcher') {
+        patchedHttpOptions[key] = value;
+        continue;
+      }
       // Records compile to objects.
-      if (typeof value === 'object') {
+      if (typeof value === 'object' && value !== null) {
         // @ts-expect-error TS2345TS7053: Element implicitly has an 'any' type
         // because expression of type 'string' can't be used to index type
         // 'HttpOptions'.
@@ -471,6 +475,11 @@ export class ApiClient {
         httpOptions.extraBody as Record<string, unknown>,
       );
     }
+    if (httpOptions && httpOptions.dispatcher) {
+      // @ts-expect-error TS2339: Property 'dispatcher' does not exist on type 'RequestInit'.
+      // This is a Node.js-specific property for undici
+      requestInit.dispatcher = httpOptions.dispatcher;
+    }
     requestInit.headers = await this.getHeadersInternal(httpOptions, url);
     return requestInit;
   }
diff --git a/src/node/node_client.ts b/src/node/node_client.ts
index 17bd0e256..d97b690a8 100644
--- a/src/node/node_client.ts
+++ b/src/node/node_client.ts
@@ -4,7 +4,9 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
+import * as fs from 'fs';
 import {GoogleAuthOptions} from 'google-auth-library';
+import {Agent} from 'undici';
 
 import {ApiClient} from '../_api_client.js';
 import {getBaseUrl} from '../_base_url.js';
@@ -158,6 +160,23 @@ export class GoogleGenAI {
       }
     }
 
+    // Configure mTLS if client certificates are provided
+    const clientCert = getClientCertFromEnv();
+    const clientKey = getClientKeyFromEnv();
+    if (clientCert && clientKey) {
+      const agent = new Agent({
+        connect: {
+          cert: clientCert,
+          key: clientKey,
+        },
+      });
+      if (options.httpOptions) {
+        options.httpOptions.dispatcher = agent;
+      } else {
+        options.httpOptions = {dispatcher: agent};
+      }
+    }
+
     this.apiVersion = options.apiVersion;
     this.httpOptions = options.httpOptions;
     const auth = new NodeAuth({
@@ -214,3 +233,43 @@ function getApiKeyFromEnv(): string | undefined {
   }
   return envGoogleApiKey || envGeminiApiKey || undefined;
 }
+
+function getClientCertFromEnv(): string | undefined {
+  const envGoogleClientCert = getEnv('GOOGLE_CLIENT_CERT');
+  const envGeminiClientCert = getEnv('GEMINI_CLIENT_CERT');
+  if (envGoogleClientCert && envGeminiClientCert) {
+    console.warn(
+      'Both GOOGLE_CLIENT_CERT and GEMINI_CLIENT_CERT are set. Using GOOGLE_CLIENT_CERT.',
+    );
+  }
+  const certPath = envGoogleClientCert || envGeminiClientCert;
+  if (certPath) {
+    try {
+      return fs.readFileSync(certPath, 'utf8');
+    } catch (error) {
+      throw new Error(
+        `Failed to read client certificate from ${certPath}: ${error}`,
+      );
+    }
+  }
+  return undefined;
+}
+
+function getClientKeyFromEnv(): string | undefined {
+  const envGoogleClientKey = getEnv('GOOGLE_CLIENT_KEY');
+  const envGeminiClientKey = getEnv('GEMINI_CLIENT_KEY');
+  if (envGoogleClientKey && envGeminiClientKey) {
+    console.warn(
+      'Both GOOGLE_CLIENT_KEY and GEMINI_CLIENT_KEY are set. Using GOOGLE_CLIENT_KEY.',
+    );
+  }
+  const keyPath = envGoogleClientKey || envGeminiClientKey;
+  if (keyPath) {
+    try {
+      return fs.readFileSync(keyPath, 'utf8');
+    } catch (error) {
+      throw new Error(`Failed to read client key from ${keyPath}: ${error}`);
+    }
+  }
+  return undefined;
+}
diff --git a/src/types.ts b/src/types.ts
index 3f48de4b3..4b089aaae 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -1572,6 +1572,9 @@ export declare interface HttpOptions {
       - VertexAI backend API docs: https://cloud.google.com/vertex-ai/docs/reference/rest
       - GeminiAPI backend API docs: https://ai.google.dev/api/rest */
   extraBody?: Record<string, unknown>;
+  /** Undici dispatcher for custom HTTP agent configuration (Node.js only).
+      This can be used to configure mTLS with client certificates. */
+  dispatcher?: unknown;
 }
 
 /** Schema is used to define the format of input/output data.