The Madness frontman will team up with Zoe Ball, while This Morning's Fern Britton and newsreader Angela Rippon are also confirmed for solo perfomances. Comic Dom Joly, athletes Martin Offiah and Denise Lewis and The Bill stars Lisa Maxwell and Patrick Robinson complete the lineup.
Strictly Come Dancing's Lisa Snowdon and comedian Dara O'Briain will join Anton Du Beke on the panel for this weekend's show.
The winning two acts will join Jo Brand, Robert Webb, Dick & Dom and Keith Lemon and Paddy McGuinness in the final on Saturday, March 14.
Denise Van Outen and stand-up Michael McIntyre have been confirmed as the judges for the final.