How to customize a TimePicker widget in Flutter

showTimePicker(
                  context: context,
                  initialTime: TimeOfDay(hour: 10, minute: 47),
                  builder: (context, child) {
                    return Theme(
                      data: ThemeData.light().copyWith(
                        colorScheme: ColorScheme.light(
                          // change the border color
                          primary: Colors.red,
                          // change the text color
                          onSurface: Colors.purple,
                        ),
                        // button colors 
                        buttonTheme: ButtonThemeData(
                          colorScheme: ColorScheme.light(
                            primary: Colors.green,
                          ),
                        ),
                      ),
                      child: child,
                    );
                  },
                );

Result:

You are able to use states on your theme too! Controlling the styles when making some action (like selected or focused actions).

Here an example:

final theme = ThemeData.light().copyWith(
  timePickerTheme: TimePickerThemeData(
    backgroundColor: Colors.green.shade200,
    hourMinuteColor: MaterialStateColor.resolveWith((states) =>
        states.contains(MaterialState.selected)
            ? Colors.blue.withOpacity(0.2)
            : Colors.orange),
    hourMinuteTextColor: MaterialStateColor.resolveWith((states) =>
        states.contains(MaterialState.selected)
            ? Colors.pink
            : Colors.deepPurple),
    dialHandColor: Colors.pink.shade800,
    dialBackgroundColor: Colors.purple.withOpacity(0.5),
    dialTextColor: MaterialStateColor.resolveWith((states) =>
        states.contains(MaterialState.selected)
            ? Colors.green
            : Colors.black),
    entryModeIconColor: Colors.yellow
    ),
    textTheme: TextTheme(
      overline: TextStyle(
        color: Colors.red,
      ),
    ),
    textButtonTheme: TextButtonThemeData(
        style: ButtonStyle(
      backgroundColor: MaterialStateColor.resolveWith((states) => Colors.black),
      foregroundColor: MaterialStateColor.resolveWith((states) => Colors.green),
      overlayColor: MaterialStateColor.resolveWith((states) => Colors.pink),
    )));