An evening of comedy and entertainment, organised partly by Gwyneth Paltrow and Cancer Research UK, will air from 7pm tonight (October 19) on the channel.
Jennifer Aniston, Kylie Minogue, George Clooney and Will Smith have backed the campaign, which is to be hosted by Alan Carr, Davina McCall and Dr Christian Jessen.
A super-sized version of Alan Carr: Chatty Man will be screened tonight, along with a special charity edition of The Million Pound Drop, with McCall teasing on Twitter that the potential prize money has been doubled to £2 million.
Other famous faces due to take part include The Simpsons, Tom Daley, Leona Lewis, Jonnie Peacock, Emeli Sandé and Jenson Button.
JLS, Jimmy Carr, Jack Whitehall, Anna Friel, the cast of 8 out of 10 Cats, The English National Ballet, Martin Freeman, Miranda Hart, Simon Bird and David Hasselhoff will also do their bit for Stand Up To Cancer.
Viewers can find out more, including how to donate to the cause, on the Stand Up To Cancer website.