Deploying a Xamarin app to the App Store and Google Play involves a series of steps to ensure compliance with platform-specific guidelines and technical requirements. For iOS deployment, developers must have an Apple Developer account and create an iOS distribution provisioning profile, configure the release build, manage iOS bundle signing, set up an iTunes Connect record, and submit the app through Visual Studio. The process includes signing the app and using the App Store provisioning profile for distribution. For Android deployment, developers need to prepare application assets, register as a Google Play Developer, configure the release build in Visual Studio, compile and build the app, and choose between manually uploading the APK to Google Play or using the Google Play Developer Publishing API. Both platforms require careful configuration and adherence to guidelines, with Apple and Google reviewing the app before it becomes available to users.