The ratings hit, which was voted the best reality show of 2012 by Digital Spy readers, will have 16 celebrities competing with their baking skills to raise cash for charity.
Paul Hollywood and Mary Berry will judge the stars' cakes, pastries and sweet treats, while Mel Giedroyc will host on her own without usual co-presenter Sue Perkins.
Comedian Jo Brand, stand-up Stephen K Amos and TV double act Lorna Watson and Ingrid Oliver are the first celebrities taking part in the challenges, which will involve Signature Bake shortbreads, Technical Bake custard slices and Showstopper Bakes with chocolate cakes.
Some of the dishes served for the judges include Brand's black forest cake, Amos's experimental flourless chocolate and stem ginger cake, Watson's white chocolate and raspberry cake and Oliver's lady grey tea and lavender shortbread.
Great British Bake Off's Comic Relief specials start on Monday, January 21 at 8pm on BBC Two.