A four-part mini-series hosted by Mel Giedroyc and judged by Paul Hollywood and Mary Berry will be shown on January 21-24.
Previously confirmed for the shows were comics Jo Brand, Stephen K Amos and double act Lorna Watson and Ingrid Oliver.
Joining them are 12 other stars who will be tackling Signature Bakes, Technical Bakes and Showstopper Bakers.
Heat two will feature Warwick Davis, Dragons' Den star Duncan Bannatyne and TV presenters Andy Akinwolere and Simon Reeve.
The third show will feature Paralympic gold medal winner Ellie Simmonds, TV presenters Julia Bradbury and Kirsty Wark and comedian Bob Mortimer.
Completing the lineup in the final show are Strictly presenter Claudia Winkleman, stand-up Ed Byrne, Olympian Helen Glover and journalist Martha Kearney.