Three songs he's featured on have appeared on the X Factor this year:

Travie McCoy ft Bruno Mars - Billionaire (performed by FYD)

Bruno Mars - Just The Way You Are (performed by Matt Cardle)

B.O.B ft Bruno Mars - Nothing on You (performed by Cher Lloyd)

Hmm wonder if he'll be one of the guest artists for the final. They seem to like his music.

Wasn't Billionaire sang by somebody at judge's houses, too?

Yes John Adeleye, when he was still cool and interesting
before Louis got hold of him and stuck him in suits and a musical timewarp