Robbie Williams will return to The X Factor on Saturday to perform with finalist Olly Murs, while favourite Joe McElderry teams up with George Michael.
Stacey Solomon will perform with singer Michael Buble.
The star-studded duets were announced by Simon Cowell at a press conference with the competition's finalists and fellow judges Dannii Minogue, Cheryl Cole and Louis Walsh ahead of the grand final.
Cowell also branded a campaign to prevent the show's winner from having the Christmas number one single as "stupid" and "cynical".
He said he felt it was "dismissive" of the show's viewers and that he felt the campaign was aimed at him.
A group set up on Facebook is calling for people to make rock band Rage Against The Machine's 1992 single Killing in the Name this year's number one.
It currently has 548,000 members.
Speaking Cowell said: "If there's a campaign, and I think the campaign's aimed directly at me, it's stupid. Me having a number one record at Christmas is not going to change my life particularly.
"It does however change these guys' lives and we put this opportunity there so that the winner of the X Factor gets the chance of having a big hit record.
"I think it's quite a cynical campaign geared at me which is actually going to spoil the party for these three."
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