Facebook has been working on a dark mode for Messenger, and it’s a true OLED black theme. It’s still hidden away right now, but ready to activate at any time using a peculiar trick. There are two methods to activate this feature — one is easy and supported by Facebook, while the other is hard but should have a 100% success rate.
The first method works for both Android and iOS, but it’s very finicky. Most users are able to trigger it if they keep trying, but it’s possible Facebook hasn’t turned the feature on for your account. So it’ll probably work, but if it doesn’t, you can wait a little bit longer. Messenger will be rolling the Dark Mode out to everyone in the settings by the end of March 2019 — without having to perform any tricks. If you still can’t wait, rooted Android users can try Method 2 below.
Send a Moon Emoji – 🌙
This is so simple it’s silly: to enable dark mode, send someone a moon emoji. The regular, left-facing crescent moon icon as seen below, not any of the moon emojis with smiley faces.
If you’moon emojis will rain down in the message thread, then a popup will appear at the top of the screen stating “You Found Dark Mode!” Tap this popup to turn the feature on.