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This guide walks you through adding OneSignal to your Android app using Android Studio. You’ll install our SDK, setup push and in-app messages, and send test messages to confirm everything is working. If this is your first time using OneSignal, follow the steps in order. If you’re experienced, feel free to jump to the sections you need.
Using an AI coding assistant? For AI-driven installation, use this prompt:
Integrate the OneSignal Android SDK into this codebase.

Follow the instructions at:
https://raw.githubusercontent.com/OneSignal/sdk-ai-prompts/main/docs/android/ai-prompt.md

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Step 0. Configure FCM in OneSignal (required to deliver push)

You can install and initialize the OneSignal Android SDK without completing this step. However, push notifications will not deliver until Firebase Cloud Messaging (FCM) credentials are configured in your OneSignal app.
If your company already has a OneSignal account, ask to be invited as an admin role to configure the app. Otherwise, sign up for a free account to get started.
These steps connect your OneSignal app to Firebase Cloud Messaging (FCM). You only need to do this once per app.
  1. Login to https://onesignal.com and create or select your App.
  2. Navigate to Settings > Push & In-App.
  3. Select Google Android (FCM) and Continue through the setup wizard.
  4. Input your Firebase Server Key or Service Account details.
  5. Continue through the setup wizard to get your App ID. This will be used to initialize the SDK.
For full setup instructions, see our Mobile push setup guide.

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Setup contract & requirements

This section summarizes the tools, versions, and assumptions used throughout the guide.
  • SDK version: 5.6.1+ (latest: check releases)
  • AI setup instructions: https://raw.githubusercontent.com/OneSignal/sdk-ai-prompts/main/docs/android/ai-prompt.md
  • SDK repo: https://github.com/OneSignal/OneSignal-Android-SDK
  • Android Studio: Meerkat+ (2024.2.1+)
  • Android API: 23+ minimum (Android 6.0+), 31+ recommended (Android 12+)
  • Device/Emulator: Android 7.0+ with Google Play Services installed
  • Required dependency: com.onesignal:OneSignal:[5.6.1, 5.6.99]
  • Application class: Required for proper SDK initialization
  • App ID format: 36-character UUID (example: 12345678-1234-1234-1234-123456789012) — find at OneSignal Dashboard > Settings > Keys & IDs
  • Initialize: OneSignal.initWithContext(this, "YOUR_APP_ID")
  • Battery Optimization: May affect background notifications
  • Recommended: Assign External ID via OneSignal.login("user_id") to unify users across devices

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Android setup steps

By the end of the steps below, you will have:
  • The OneSignal SDK installed and initialized in your Android app
  • Push notification permissions prompting correctly on a real device
  • A test push and in-app message successfully delivered
If you skipped Step 0 (Configuring FCM in OneSignal), you can still complete the Android Studio setup below. Complete Step 0 before you test or send push notifications.

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Step 1. Add the OneSignal SDK

  1. In Android Studio, open your build.gradle.kts (Module: app) or build.gradle (Module: app) file
  2. Add OneSignal to your dependencies section:
implementation("com.onesignal:OneSignal:[5.6.1, 5.6.99]")
  1. Sync Gradle: Click Sync Now in the banner that appears or go to File > Sync Project with Gradle Files
Verify that the gradle sync completes successfully without dependency conflicts.

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Step 2. Create and configure Application class

It’s best practice to initialize OneSignal in the onCreate method of your Application class to ensure proper SDK setup across all entry points. Create an Application class if you don’t already have one:
  1. File > New > Kotlin Class/File (or Java Class)
  2. Name: ApplicationClass (or your preferred name)
Add the following OneSignal code to the Application class. Replace YOUR_APP_ID with your actual OneSignal App ID from the Dashboard > Settings > Keys & IDs. 
// FILE: ApplicationClass.kt
// PURPOSE: Initialize OneSignal when your app launches
// REQUIREMENT: Must be registered in AndroidManifest.xml

package com.your.package.name // Replace with your actual package name

import android.app.Application
import kotlinx.coroutines.CoroutineScope
import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.launch

import com.onesignal.OneSignal
import com.onesignal.debug.LogLevel

class ApplicationClass : Application() {
    override fun onCreate() {
        super.onCreate()

        // Enable verbose logging to debug issues (remove in production)
        OneSignal.Debug.logLevel = LogLevel.VERBOSE

        // Replace with your 36-character App ID from Dashboard > Settings > Keys & IDs
        OneSignal.initWithContext(this, "YOUR_APP_ID")

        // Prompt user for push notification permission
        // In production, consider using an in-app message instead for better opt-in rates
        CoroutineScope(Dispatchers.IO).launch {
            OneSignal.Notifications.requestPermission(false)
        }
    }
}
Initializing in an Activity (like MainActivity) is not recommended because it may not be called on app cold-starts from deep links or notifications. Always initialize OneSignal in your Application class for reliability.
Register the Application class:
  1. Open your app’s AndroidManifest.xml
  2. In your <application> tag add android:name=".ApplicationClass" (replace .ApplicationClass with your actual class name if set it to something different).
AndroidManifest.xml
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools">

    <application
        android:name=".ApplicationClass"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        ...
      </application>

  </manifest>
Verify that the app builds and runs without errors.
Customize notification icons to match your app’s branding. This step is optional but recommended for a professional appearance.

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Step 4. Test the integration

Verify Subscription creation:
  1. Launch app on device or emulator with Google Play Services
  2. Check Dashboard > Audience > Subscriptions — status shows “Never Subscribed”
  3. Accept the permission prompt when it appears
  4. Refresh dashboard — status changes to “Subscribed”
Example of the iOS and Android push permission prompts.
Dashboard showing Subscription with 'Never Subscribed' status.
After allowing push permissions, refresh the dashboard to see the Subscription status update to 'Subscribed'.
You have successfully created a mobile Subscription. Mobile subscriptions are created when users first open your app on a device or if they uninstall and reinstall your app on the same device.

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Create test Subscription and segment

  1. Click ⋮ next to the Subscription > Add to Test Subscriptions > name it
  2. Go to Audience > Segments > New Segment
  3. Name: Test Users, add filter Test Users > Create Segment
Add a Test Subscription.
Create a 'Test Users' segment with the Test Users filter.
You have successfully created a segment of test users.We can now test sending messages to this individual device and groups of test users.

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Send test push via API

  1. Navigate to Settings > Keys & IDs.
  2. In the provided code, replace YOUR_APP_API_KEY and YOUR_APP_ID in the code below with your actual keys. This code uses the Test Users segment we created earlier.
curl -X POST 'https://api.onesignal.com/notifications' \
  -H 'Content-Type: application/json; charset=utf-8' \
  -H 'Authorization: Key YOUR_APP_API_KEY' \
  -d '{
    "app_id": "YOUR_APP_ID",
    "target_channel": "push",
    "name": "Testing basic setup",
    "headings": { "en": "👋" },
    "contents": {"en": "Hello world!"},
    "included_segments": ["Test Users"],
    "big_picture": "https://avatars.githubusercontent.com/u/11823027?s=200&v=4"
  }'
Images in push notifications appear small in the collapsed notification view. Expand the notification to see the full image.
Delivery stats showing confirmed delivery (unavailable on free plans).
Verify the test device received a notification with:
  • Your custom icon (if configured)
  • Large image when expanded
  • Dashboard > Delivery > Sent Messages shows “Confirmed” status (unavailable on free plans).
  • No notification received? See Mobile push not shown.
  • No custom icon? Verify the icon name is onesignal_small_icon_default and in the correct drawable folders.
  • Having issues? Copy-paste the api request and a log from start to finish of app launch into a .txt file. Then share both with support@onesignal.com.

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Test in-app messages

  1. Close app for 30+ seconds
  2. Dashboard > Messages > In-App > New In-App > select Welcome template
  3. Audience: Test Users segment
  4. Trigger: On app open
  5. Schedule: Every time trigger conditions are satisfied
  6. Click Make Message Live
  7. Open app
Targeting the 'Test Users' segment with an in-app message.
Example customization of in-app Welcome message.
In-app message scheduling options.
Welcome in-app message shown on devices.
Verify the test device received an in-app message. See the In-app messages setup guide for more details.
Not seeing the message?
  • Start a new session
    • You must close or background the app for at least 30 seconds before reopening. This ensures a new session is started.
    • For more, see how in-app messages are displayed.
  • Still in the Test Users segment?
    • If you reinstalled or switched devices, re-add the device to Test Subscriptions and confirm it’s part of the Test Users segment.
  • Having issues?
    • Follow Getting a Debug Log while reproducing the steps above. This will generate additional logging that you can share with support@onesignal.com and we will help investigate what’s going on.
You have successfully set up the OneSignal SDK and learned important concepts like:Continue with this guide to identify users in your app and setup additional features.

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Common Errors & Fixes

Error / SymptomCauseFix
Cannot resolve symbol 'OneSignal'SDK dependency not added or gradle not syncedAdd dependency to build.gradle and sync project
Application class not foundApplication class not registered in manifestAdd android:name=".ApplicationClass" to <application> tag
Google Play Services not availableEmulator/device missing Play ServicesUse device with Play Store or emulator with Google APIs
Push received but default Android iconCustom icon not configured or wrong nameCreate notification icon asset named onesignal_small_icon_default
No push notifications receivedFCM not configured in OneSignalComplete Step 0: Configure FCM credentials in OneSignal dashboard
In-app messages not showingSession not started or network issuesClose app 30+ seconds, reopen, check internet connection
Manifest merger failedConflicting manifest attributesCheck for duplicate application names or permissions conflicts
Battery optimization blocking notificationsDevice power managementGuide users to disable battery optimization for your app
Can’t diagnose issueNot enough log infoAdd verbose logging and check logcat output for errors

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User management

Previously, we demonstrated how to create mobile Subscriptions. Now we’ll expand to identifying Users across all their Subscriptions (including push, email, and SMS) using the OneSignal SDK. Use an External ID to identify users consistently across devices, email addresses, and phone numbers using your backend’s user identifier. This ensures your messaging stays unified across channels and 3rd party systems. See our Mobile SDK reference for more details and Java code examples.
Kotlin
// Call when user logs in or is identified, safe to call multiple times
// Typically used in a login completion handler, or on app launch if already authenticated
fun onUserAuthenticated(userId: String) {
    OneSignal.login(userId)
}

// If you want to remove the External ID from the Subscription, setting it to an anonymous user
fun onUserLoggedOut() {
    OneSignal.logout()
}
OneSignal generates unique read-only IDs for Subscriptions (Subscription ID) and Users (OneSignal ID).Setting the External ID via our SDK is highly recommended to identify users across all their subscriptions, regardless of how they are created.Learn more about the login method in the SDK reference guide.

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Add Tags & Custom Events

Tags and Custom Events are both ways to add data to your users. Tags are key-value strings and are generally associated with user properties (like username, role, or status) while Custom Events have a JSON format and are usually associated with actions (like new_purchase, abandoned_cart, and associated properties). Both can be used to power advanced Message Personalization and Journeys. See our Mobile SDK reference for more details and Java code examples.
Kotlin
// Add a tag when the user's name is set
OneSignal.User.addTag("username", "john_doe")

// Create a custom event when user abandoned a cart
val properties = mapOf(
    "product_id" to "123456",
    "product_name" to "Product Name",
    "product_price" to 100,
    "product_quantity" to 1
)
OneSignal.User.trackEvent("abandoned_cart", properties)
More details on how to use Tags and Custom Events in the Tags and Custom Events guides.

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Add email and/or SMS subscriptions

You can reach users through email and SMS channels in addition to push notifications. If the email address and/or phone number already exist in the OneSignal app, the SDK will add it to the existing user — it will not create duplicates. See our Mobile SDK reference for more details and Java code examples.
Kotlin
// Add email subscription
// Call when user provides their email (e.g., account creation, settings update) after calling OneSignal.login("user_id")
OneSignal.User.addEmail("user@example.com")

// Add SMS subscription
// Use E.164 format: + country code + number
// Call when user provides their phone number (e.g., account creation, settings update) after calling OneSignal.login("user_id")
OneSignal.User.addSms("+15551234567")
A user profile with push, email, and SMS subscriptions unified by External ID.
Best practices for multi-channel communication
  • Obtain explicit consent before adding email or SMS subscriptions.
  • Explain the benefits of each communication channel to users.
  • Provide channel preferences so users can select which channels they prefer.
To control when OneSignal collects user data, use the SDK’s consent gating methods. See our Mobile SDK reference for more details and Java code examples.
Kotlin
// In ApplicationClass onCreate(), BEFORE OneSignal.initWithContext()
// Use this if your app requires GDPR or other privacy consent before data collection
OneSignal.consentRequired = true

// Later, after user grants consent (e.g., taps "I Agree" on your consent screen)
OneSignal.consentGiven = true
See our Privacy & security docs for more on:

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Prompt for push permissions

Instead of calling requestPermission() immediately on app open, take a more strategic approach. Use an in-app message to explain the value of push notifications before requesting permission. For best practices and implementation details, see our Prompt for push permissions guide.

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Listen to push, user, and in-app events

Use SDK listeners to react to user actions and state changes. Add these in your Application class after OneSignal.initWithContext().

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Push notification events

Kotlin
// Add click listener to handle when users tap notifications
val clickListener = object : INotificationClickListener {
  override fun onClick(event: INotificationClickEvent) {
    Log.d("OneSignal", "Notification clicked: ${event.notification.title}")
  }
}
OneSignal.Notifications.addClickListener(clickListener)

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User state changes

Example shows how to use push subscription observer. Other user state events like the user state observer and notification permission observer are available in the Mobile SDK Reference.
Kotlin
// Add subscription observer to track push subscription changes
class MyObserver : IPushSubscriptionObserver {
  init {
    OneSignal.User.pushSubscription.addObserver(this)
  }

  override fun onPushSubscriptionChange(state: PushSubscriptionChangedState) {
    if (state.current.optedIn) {
      println("User is now opted-in with push token: ${state.current.token}")
    }
  }
}

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In-app message events

Additional in-app message methods are available in the Mobile SDK Reference.
Kotlin
// Add click listener for in-app message interactions
val clickListener = object : IInAppMessageClickListener {
  override fun onClick(event: IInAppMessageClickEvent) {
    print(event.result.actionId)
  }
}
OneSignal.InAppMessages.addClickListener(clickListener)

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Advanced setup & capabilities

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Android-specific features

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Universal features

For full SDK method documentation, visit the Mobile SDK Reference.
Need help?Chat with our Support team or email support@onesignal.comPlease include:
  • Details of the issue you’re experiencing and steps to reproduce if available
  • Your OneSignal App ID
  • The External ID or Subscription ID if applicable
  • The URL to the message you tested in the OneSignal Dashboard if applicable
  • Any relevant logs or error messages
We’re happy to help!