How I Integrated Google Sign-In in Flutter in 15 Minutes (Android + iOS)

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Skip the fluff. Let's implement what matters — because I know why you're here.

If you're reading this, you're probably in the middle of building a Flutter app and just need one thing working right now: Google Sign-In.

No fluff, no endless intros. Just a clean, reliable implementation that works for both Android and iOS in 2025. As someone who's been crafting mobile apps for 8+ years, I'll guide you through exactly what I use in real-world production.

Let's get your users logging in.

✅ What You'll Learn

How to integrate Google Sign-In into your Flutter app (2025-ready)
Set up for both Android and iOS platforms
Clean UI and managing authentication state
A full working example you can copy and use

Just follow all the steps listed below and get your app equipped with the Google Sign-In.

1. 🧰 Required Packages

Add these to your pubspec.yaml file:

dependencies:
  google_sign_in: ^6.2.1
  firebase_auth: ^4.17.3
  firebase_core: ^3.3.2

Then run:

flutter pub get

2. 🔧 Firebase Setup

Make sure your app is connected to Firebase. You only need to follow the official setup guide once:

👉 How to initialise Firebase in your Flutter app (2025 guide). Check and initialize the Firebase project first if it is pending yet, before going ahead.

You'll need to register both the Android and iOS versions of your app there.

Go to the Firebase Console
Open your project → Authentication → Sign-in method
Enable Google under sign-in providers
Add a support email
Save and you're done!

4. 🧭 Android Configuration

In android/app/build.gradleMake sure this is set:

defaultConfig {
    ...
    minSdkVersion 21
}

Then in android/app/src/main/AndroidManifest.xml, add:

<application>
    ...
    <meta-data
        android:name="com.google.android.gms.client_id"
        android:value="@string/default_web_client_id"/>
</application>

Also, download google-services.json from Firebase and place it inside android/app If you initialize the Firebase project manually, and not with the Firebase CLI.

5. 🍏 iOS Configuration

Download GoogleService-Info.plist from Firebase (Skip it if you initialize the Firebase project by the Firebase CLI.)
Place it in ios/Runner/ (Skip it also if you initialize the Firebase project by the Firebase CLI.)
In ios/Runner/Info.plist, add:

<key>CFBundleURLTypes</key>
<array>
  <dict>
    <key>CFBundleURLSchemes</key>
    <array>
      <string>YOUR_CLIENT_ID</string>
    </array>
  </dict>
</array>

Make sure to replace YOUR_CLIENT_ID With the actual value from your plist file.

Then run:

cd ios
pod install

6. 🧪 Dart Code Example

Here's a full working Flutter example with Google Sign-In:

import 'package:flutter/material.dart';
import 'package:firebase_core/firebase_core.dart';
import 'package:firebase_auth/firebase_auth.dart';
import 'package:google_sign_in/google_sign_in.dart';

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await Firebase.initializeApp();
  runApp(MyApp());
}
class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Google Sign-In Demo',
      home: AuthScreen(),
    );
  }
}
class AuthScreen extends StatefulWidget {
  @override
  State<AuthScreen> createState() => _AuthScreenState();
}
class _AuthScreenState extends State<AuthScreen> {
  User? user;
  Future<void> signInWithGoogle() async {
    final googleUser = await GoogleSignIn().signIn();
    if (googleUser == null) return; // User canceled
    final googleAuth = await googleUser.authentication;
    final credential = GoogleAuthProvider.credential(
      accessToken: googleAuth.accessToken,
      idToken: googleAuth.idToken,
    );
    final userCredential = await FirebaseAuth.instance.signInWithCredential(credential);
    setState(() => user = userCredential.user);
  }
  void signOut() async {
    await GoogleSignIn().signOut();
    await FirebaseAuth.instance.signOut();
    setState(() => user = null);
  }
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text("Google Sign-In")),
      body: Center(
        child: user == null
            ? ElevatedButton(
                onPressed: signInWithGoogle,
                child: Text("Sign in with Google"),
              )
            : Column(
                mainAxisAlignment: MainAxisAlignment.center,
                children: [
                  CircleAvatar(
                    backgroundImage: NetworkImage(user!.photoURL ?? ""),
                    radius: 40,
                  ),
                  SizedBox(height: 10),
                  Text("Welcome, ${user!.displayName}"),
                  Text(user!.email ?? ''),
                  SizedBox(height: 20),
                  ElevatedButton(
                    onPressed: signOut,
                    child: Text("Logout"),
                  ),
                ],
              ),
      ),
    );
  }
}

Once set up, the app lets users sign in with Google and displays their profile picture, name, and email. Works on both Android and iOS without platform issues.

✍️ Why There's No Long Intro

You already know what Google Sign-In is and why you need it. So I've cut straight to the part that matters — getting it working fast and error-free.

But if you want a deep dive comparing Google Auth with email/password login, let me know — I'll write it.

🛡️ Extra Tips

Always test on real devices. Emulators often fail with Google auth.
If switching accounts, call GoogleSignIn().signOut() first.
Don't forget to add both SHA-1 and SHA-256 keys in the Firebase Console.

💛 A Little Help, A Lot of Impact

Creating helpful Flutter content takes hours — but sharing it with you is my passion.
If you'd like to express your gratitude, you can send a small tip or donation. Every bit helps me stay focused and also chip away at some personal debt.

👉 Donate on PayPal

Every little bit helps and means a lot. Thank you!

👋 Final Thoughts

Google Sign-In in Flutter is straightforward, but missing just one step can cause headaches. This guide is designed as a copy-paste-ready solution, I wish I had early on.

If it helped, feel free to bookmark it, share it with your team, or follow for more practical Flutter tutorials — no fluff, just solutions.