Justin Bieber will perform a new song he's recorded with Boyz II Men on "Dancing with the Stars" ... TooFab has learned exclusively.
We're told Justin and Boyz will perform "Fa La La" -- a cappella -- on the results show next Tuesday.
We snagged a video of Justin and the men from Boyz recording the song. "Fa La La" is a track on Bieber's holiday album "Under the Mistletoe."
Check it out above!