The former Take That singer - who recently announced three dates at London's O2 Arena - is said to be making an appearance as guest judge before performing his single 'Candy' on November 4.
"The idea is to get the famous acts more involved in the show and the decision making," said an X Factor source.
"Others being approached include Bruno Mars, Pink and Gwen Stefani. They would be there to give their opinion as unbiased judges without having a vested interest in any of the acts."
Simon Cowell is also rumoured to be returning to the series as a fifth judge. Producers are thought to be keen for the 52-year-old music mogul to join Tulisa Contostavlos, Nicole Scherzinger, Gary Barlow and Louis Walsh for the final December show in a surprise twist.
"Producers know that having him criticising and judging the other judges would be TV gold," the source added.
The X Factor live shows continue tonight at 8pm, with performances by Leona Lewis and Ne-Yo.
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