Show judge Paul Hollywood confirmed plans for a charity special during an appearance at a live baking show at the weekend.
Match of the Day host Gary Lineker, comic Michael McIntyre and comic actress Miranda Hart will compete in the series, according to The Mirror.
Great British Bake Off will return for a full fourth series at the end of 2013.
Judges Hollywood and Mary Berry have both landed their own individual cookery shows, which will also air next year.
The third series of Bake Off was a ratings smash for the BBC Two, pulling in over five million viewers for the channel.