Yes! iHeartRadio app for Android supports dark mode. 

By default, dark mode is controlled by your device’s settings. If your device is set to dark mode, the iHeartRadio app will appear in dark mode automatically. If your device’s theme changes automatically based on the time of day or room brightness, the iHeartRadio app will do the same.

You can also go into your iHeartRadio app settings by tapping on the gear icon at the top left of the app, and scroll down to Theming to manually change to Light mode, Dark mode, or System default.