Sir Elton, Gary Barlow, One Direction, Katy Perry, the Killers and Tom Odell are among the entertainers scheduled for The X Factor UK's Season 10 finale.
ITV will televise it in two parts on Saturday, December 14, and during the following evening. The winner will be announced on the 15th.
Barlow is a judge on the show, but and has announced that 2013 is his last year. He became a judge in 2011.
Elton has been an outspoken critic of The X Factor and other TV talent shows.
It's believed he is doing the performance as a favor to Barlow. They are expected to sing their new duet, Face to Face, on the December 15th broadcast.