Strictly Come Dancing winner Louis Smith, comic Ronnie Corbett and supermodel Elle Macpherson are among the guests who will take part in Graham Norton's bid to set a new TV chat show record.
The presenter is to take over BBC3 for an entire evening for a marathon programme with guests arriving back to back in the run-up to Red Nose Day.
Comic Relief's Big Chat with Graham Norton is being broadcast on March 7 and is due to last for at least six hours.
The aim is to establish a new Guinness World Record for the most questions asked on a TV chat show.
Other guests lined up include Sarah Millican, Martin Freeman, Jimmy Carr, James Nesbitt, Heston Blumenthal and Kirstie Allsopp. Musical performers will include Example, Paloma Faith and Laura Mvula.
Norton said: "David Walliams swam the Thames, John Bishop endured a week of hell and Eddie Izzard ran marathon after marathon after marathon.
"I am hoping to join this elite group of celebrity fundraisers by doing what I do best - sitting on my backside and talking."
Other guest hosts during the evening will include Sir Terry Wogan and Frank Skinner, as well as Radio 1 breakfast show host Nick Grimshaw.