Outgoing BBC star Jonathan Ross is to join comedians such as Michael McIntyre, Rob Brydon and Jack Dee by starring in a live comedy gala for Channel 4.
The event will be staged in front of 14,000 people at London's O2 Arena.
The bill of 20 comics for the March 30 show also includes Alan Carr, David Mitchell, Rich Hall and Bill Bailey.
Channel 4's Comedy Gala, to be filmed and screened by the station in April, will raise cash for Great Ormond Street Children's Hospital.
Ross is due to leave the BBC in July when his contract runs out, and Channel 4's programme chief Julian Bellamy recently said he had been "in touch" with the presenter.
Ross's agent is the executive producer of the event.
Other stars taking part in next month's show are Jo Brand, Lee Evans, Mark Watson and Omid Djalili. A number of the stars taking part such as Brand, Brydon, Djalili and Dee are better known for their BBC pedigree.
Channel 4's head of entertainment, Justin Gorman, said: "We're incredibly proud of the talent we have on the channel. We are very pleased that so many other comedians and celebrities are joining us for what we fully intend to be the comedy event of the year."
Funds from the event will pay for new anaesthetic rooms at the children's hospital.
Chief executive Dr Jane Collins said: "This great night out will help raise much-needed money to allow us to continue to help sick children."