.
└── android
    └── app
        └── src
            └── main
                └── AndroidManifest.xml

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.fluttergooglemap">

    <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>
    <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/>

    <application
        android:name="io.flutter.app.FlutterApplication"
        android:label="fluttergooglemap"
        android:icon="@mipmap/ic_launcher">

        <meta-data android:name="com.google.android.geo.API_KEY"
            android:value="YOUR API KEY"/>

        <activity
            android:name=".MainActivity"
            ...

.
└── ios
    └── Runner
        ├── AppDelegate.swift
        └── Info.plist

@UIApplicationMain
@objc class AppDelegate: FlutterAppDelegate {
  override func application(
    _ application: UIApplication,
    didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?
  ) -> Bool {
  GMSServices.provideAPIKey("YOUR API KEY")
    GeneratedPluginRegistrant.register(with: self)
    return super.application(application, didFinishLaunchingWithOptions: launchOptions)
  }
}

<dict>
     <key>NSLocationWhenInUseUsageDescription</key>
          <string>This app needs your location to test the location feature of the Google Maps plugin.</string>
          <key>io.flutter.embedded_views_preview</key>
          <true/>
     ...

dependencies:
  flutter:
    sdk: flutter

  google_maps_flutter: ^0.5.28+1

  ...

import 'package:google_maps_flutter/google_maps_flutter.dart';

class _MyHomePageState extends State<MyHomePage> {

  Completer<GoogleMapController> _controller = Completer();

 @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: GoogleMap(
        initialCameraPosition: CameraPosition(
          target: LatLng(13.757429, 100.502465), //กำหนดพิกัดเริ่มต้นบนแผนที่
          zoom: 15, //กำหนดระยะการซูม สามารถกำหนดค่าได้ 0-20
        ),
        onMapCreated: (GoogleMapController controller) {
          _controller.complete(controller);
        },
      ),
    );
  }