diff --git a/packages/cli/src/utils/sandbox.test.ts b/packages/cli/src/utils/sandbox.test.ts
index 1dda7b355a..256b418e83 100644
--- a/packages/cli/src/utils/sandbox.test.ts
+++ b/packages/cli/src/utils/sandbox.test.ts
@@ -719,6 +719,65 @@ describe('sandbox', () => {
       expect(entrypointCmd).toContain('su -p gemini');
     });
 
+    it('should register and unregister proxy exit handlers', async () => {
+      vi.stubEnv('GEMINI_SANDBOX_PROXY_COMMAND', 'some-proxy-cmd');
+      const config: SandboxConfig = createMockSandboxConfig({
+        command: 'docker',
+        image: 'gemini-cli-sandbox',
+      });
+
+      const onSpy = vi.spyOn(process, 'on');
+      const offSpy = vi.spyOn(process, 'off');
+
+      interface MockProcessWithStdout extends EventEmitter {
+        stdout: EventEmitter;
+      }
+
+      vi.mocked(spawn).mockImplementation((cmd, args) => {
+        const a = args as string[];
+        if (cmd === 'docker' && a && a[0] === 'images') {
+          const mockImageCheckProcess =
+            new EventEmitter() as MockProcessWithStdout;
+          mockImageCheckProcess.stdout = new EventEmitter();
+          setTimeout(() => {
+            mockImageCheckProcess.stdout.emit('data', Buffer.from('image-id'));
+            mockImageCheckProcess.emit('close', 0);
+          }, 1);
+          return mockImageCheckProcess as unknown as ReturnType<typeof spawn>;
+        }
+        if (cmd === 'docker' && a && a[0] === 'run') {
+          const mockSpawnProcess = new EventEmitter() as unknown as ReturnType<
+            typeof spawn
+          >;
+          mockSpawnProcess.on = vi.fn().mockImplementation((event, cb) => {
+            if (event === 'close') {
+              if (a.includes('gemini-cli-sandbox-proxy')) {
+                // Proxy container shouldn't exit during the test
+              } else {
+                setTimeout(() => cb(0), 10);
+              }
+            }
+            return mockSpawnProcess;
+          });
+          return mockSpawnProcess;
+        }
+        return new EventEmitter() as unknown as ReturnType<typeof spawn>;
+      });
+
+      await start_sandbox(config);
+
+      expect(onSpy).toHaveBeenCalledWith('exit', expect.any(Function));
+      expect(onSpy).toHaveBeenCalledWith('SIGINT', expect.any(Function));
+      expect(onSpy).toHaveBeenCalledWith('SIGTERM', expect.any(Function));
+
+      expect(offSpy).toHaveBeenCalledWith('exit', expect.any(Function));
+      expect(offSpy).toHaveBeenCalledWith('SIGINT', expect.any(Function));
+      expect(offSpy).toHaveBeenCalledWith('SIGTERM', expect.any(Function));
+
+      onSpy.mockRestore();
+      offSpy.mockRestore();
+    });
+
     describe('LXC sandbox', () => {
       const LXC_RUNNING = JSON.stringify([
         { name: 'gemini-sandbox', status: 'Running' },
diff --git a/packages/cli/src/utils/sandbox.ts b/packages/cli/src/utils/sandbox.ts
index 6001725cdd..ccd1f2e608 100644
--- a/packages/cli/src/utils/sandbox.ts
+++ b/packages/cli/src/utils/sandbox.ts
@@ -55,6 +55,8 @@ export async function start_sandbox(
   });
   patcher.patch();
 
+  let stopProxy: (() => void) | undefined = undefined;
+
   try {
     if (config.command === 'sandbox-exec') {
       // disallow BUILD_SANDBOX
@@ -188,17 +190,18 @@ export async function start_sandbox(
           detached: true,
         });
         // install handlers to stop proxy on exit/signal
-        const stopProxy = () => {
+        stopProxy = () => {
           debugLogger.log('stopping proxy ...');
           if (proxyProcess?.pid) {
-            process.kill(-proxyProcess.pid, 'SIGTERM');
+            try {
+              process.kill(-proxyProcess.pid, 'SIGTERM');
+            } catch {
+              // ignore
+            }
           }
         };
-        process.off('exit', stopProxy);
         process.on('exit', stopProxy);
-        process.off('SIGINT', stopProxy);
         process.on('SIGINT', stopProxy);
-        process.off('SIGTERM', stopProxy);
         process.on('SIGTERM', stopProxy);
 
         // commented out as it disrupts ink rendering
@@ -746,15 +749,18 @@ export async function start_sandbox(
         detached: true,
       });
       // install handlers to stop proxy on exit/signal
-      const stopProxy = () => {
+      stopProxy = () => {
         debugLogger.log('stopping proxy container ...');
-        execSync(`${command} rm -f ${SANDBOX_PROXY_NAME}`);
+        try {
+          spawnSync(command, ['rm', '-f', SANDBOX_PROXY_NAME], {
+            stdio: 'ignore',
+          });
+        } catch {
+          // ignore
+        }
       };
-      process.off('exit', stopProxy);
       process.on('exit', stopProxy);
-      process.off('SIGINT', stopProxy);
       process.on('SIGINT', stopProxy);
-      process.off('SIGTERM', stopProxy);
       process.on('SIGTERM', stopProxy);
 
       // commented out as it disrupts ink rendering
@@ -806,6 +812,12 @@ export async function start_sandbox(
       });
     });
   } finally {
+    if (stopProxy) {
+      stopProxy();
+      process.off('exit', stopProxy);
+      process.off('SIGINT', stopProxy);
+      process.off('SIGTERM', stopProxy);
+    }
     patcher.cleanup();
   }
 }