diff --git a/packages/core/src/ide/ide-client.test.ts b/packages/core/src/ide/ide-client.test.ts
index 1881d91122b..7ec7e53124a 100644
--- a/packages/core/src/ide/ide-client.test.ts
+++ b/packages/core/src/ide/ide-client.test.ts
@@ -59,6 +59,7 @@ describe('IdeClient', () => {
     delete process.env['GEMINI_CLI_IDE_SERVER_PORT'];
     delete process.env['GEMINI_CLI_IDE_SERVER_STDIO_COMMAND'];
     delete process.env['GEMINI_CLI_IDE_SERVER_STDIO_ARGS'];
+    delete process.env['GEMINI_CLI_IDE_AUTH_TOKEN'];
 
     // Mock dependencies
     vi.spyOn(process, 'cwd').mockReturnValue('/test/workspace/sub-dir');
@@ -923,5 +924,35 @@ describe('IdeClient', () => {
         IDEConnectionStatus.Connected,
       );
     });
+
+    it('should connect with an auth token from environment variable if config file is missing', async () => {
+      vi.mocked(fs.promises.readFile).mockRejectedValue(
+        new Error('File not found'),
+      );
+      (
+        vi.mocked(fs.promises.readdir) as Mock<
+          (path: fs.PathLike) => Promise<string[]>
+        >
+      ).mockResolvedValue([]);
+      process.env['GEMINI_CLI_IDE_SERVER_PORT'] = '9090';
+      process.env['GEMINI_CLI_IDE_AUTH_TOKEN'] = 'env-auth-token';
+
+      const ideClient = await IdeClient.getInstance();
+      await ideClient.connect();
+
+      expect(StreamableHTTPClientTransport).toHaveBeenCalledWith(
+        new URL('http://127.0.0.1:9090/mcp'),
+        expect.objectContaining({
+          requestInit: {
+            headers: {
+              Authorization: 'Bearer env-auth-token',
+            },
+          },
+        }),
+      );
+      expect(ideClient.getConnectionStatus().status).toBe(
+        IDEConnectionStatus.Connected,
+      );
+    });
   });
 });
diff --git a/packages/core/src/ide/ide-client.ts b/packages/core/src/ide/ide-client.ts
index f9b105372b2..997a2d47294 100644
--- a/packages/core/src/ide/ide-client.ts
+++ b/packages/core/src/ide/ide-client.ts
@@ -151,9 +151,10 @@ export class IdeClient {
     this.setState(IDEConnectionStatus.Connecting);
 
     this.connectionConfig = await this.getConnectionConfigFromFile();
-    if (this.connectionConfig?.authToken) {
-      this.authToken = this.connectionConfig.authToken;
-    }
+    this.authToken =
+      this.connectionConfig?.authToken ??
+      process.env['GEMINI_CLI_IDE_AUTH_TOKEN'];
+
     const workspacePath =
       this.connectionConfig?.workspacePath ??
       process.env['GEMINI_CLI_IDE_WORKSPACE_PATH'];