How to build react native android app for production?

You will have to create a key to sign the apk. Use below to create your key:

keytool -genkey -v -keystore my-app-key.keystore -alias my-app-alias -keyalg RSA -keysize 2048 -validity 10000

Use a password when prompted

Once the key is generated, use it to generate the installable build:

react-native bundle --platform android --dev false --entry-file index.android.js \
  --bundle-output android/app/src/main/assets/index.android.bundle \
  --assets-dest android/app/src/main/res/

Generate the build using gradle

cd android && ./gradlew assembleRelease

Upload the APK to your phone. The -r flag will replace the existing app (if it exists)

adb install -r ./app/build/outputs/apk/app-release-unsigned.apk

A more detailed description is mentioned here: https://facebook.github.io/react-native/docs/signed-apk-android.html

To build a release version of your Android app:

$ cd your-app-folder
$ cd android && ./gradlew assembleRelease

You'll need to set up signing keys for the Play Store, full documentation here: https://reactnative.dev/docs/signed-apk-android

As for me, I add in my package.json to "scripts":

"release": "cd android && ./gradlew assembleRelease"

And then in terminal I use:

npm run release

Or with yarn:

yarn release