After debuting the feature on desktop, YouTube has started rolling out dark mode for mobile. The streaming site starts off with iOS and will be “coming soon” to Android. You can access the new theme by tapping on the account icon and heading to settings and then just select “dark theme.” The feature not only gives the app a more cinematic look but it is a bit easier on the eyes when you try and watch YouTube videos in the dark.
Source: The Verge