@Sean said in Is a 4K MagicMirror possible?:

Impossible with rpi. But other sbc or pc might.

Sorry to bring an old thread up from the dead but since this came up as the first result when searching on google thought I would reply to it.

4K does appear to be possible on the Pi. Set one up this weekend on a TCL 4K display. Is very stable and works well even with 3 RTSP streams also running on the page. Obviously the font becomes very small with the 4K resolution so had to change font sizes but not too difficult.