Floating action button with text label. Flutter

You don't need to use an external library because it will grow the size of your bundle.

This is the code:

FloatingActionButton.extended(
    onPressed: () {
      // Add your onPressed code here!
    },
    label: Text('Approve'),
    icon: Icon(Icons.thumb_up),
    backgroundColor: Colors.pink,
) 

You can use this flutter package flutter_fab Or you can refer from this article Create Animated FAB in flutter.