There are two device screen orientation present in every mobile or Tablet device Landscape and Portrait. In mobile devices the default screen orientation mode is portrait. Every mobile phone has a Auto Rotation button present on Scrollable Menu bar. By default the Auto Rotation is disabled in mobile phones but we can enable them via Menu bar and the complete mobile phone screen will rotate on device rotation. But sometimes app developer wants to prevent Landscape mode and active only Portrait mode in flutter application. Here comes the DeviceOrientation.portraitUp method of SystemChrome package.