A girl group collaboration, the Vicar of Dibley's finale and a celebrity version of The Apprentice will be among this year's Comic Relief highlights.
The Sugababes with Girls Aloud, Lenny Henry and Davina McCall
Sugababes and Girls Aloud have teamed up on this year's Comic Relief single, a cover of Aerosmith's Walk This Way.
The pop stars donned their red noses to launch the charity appeal in the shadow of the London Eye.
With them were comedians Russell Brand and Lenny Henry, two of the hosts for BBC One's Red Nose Night on 16 March.
Kimberley Walsh of Girls Aloud said: "It's a fantastic song and hopefully will raise tons of money for people living in really difficult situations here and in Africa."
Red Nose Night will feature the last ever episode of the Vicar of Dibley, with a special guest appearance by Sting.
Comic Relief Does The Apprentice will see Sir Alan Sugar matching 10 celebrities - including Ross Kemp, Rupert Everett and Cheryl Cole - against each other.
Comic Relief does Fame Academy, hosted by Patrick Kielty and Claudia Winkleman, will also be part of this year's festivities.
And BBC Radio 1 DJ Chris Moyles will tour the nation hosting a series of karaoke nights.
This is the 11th Red Nose Day and the 21st year of Comic Relief.
The charity has raised more than £425m and sold more than 45 million red noses to date.