How to change package name in flutter?

For Android

To change the package name we just need to update appliationid in build build.gradle only

defaultConfig {
applicationId "your.package.name"
minSdkVersion 16
targetSdkVersion 27
versionCode 1
versionName "1.0"
testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
}

For iOS

Change the bundle identifier from your Info.plist file inside your ios/Runner directory

<key>CFBundleIdentifier</key>
<string>com.your.packagename</string>