John Bishop is to cycle, row and run from the Eiffel Tower to Trafalgar Square for Sport Relief.
The comic is hoping to complete the gruelling 290-mile triathlon in less than five days, in what he calls ‘the biggest physical challenge of my life’.
He will start what the charity calls ‘Bishop's Week Of Hell’ on February 27, with a 185-mile bike ride from Paris to the French coast.
Then he will row to the UK, accompanied by a team celebrity rowers including Andrew Flintoff and Davina McCall. before doing three marathons in three days to get to London. For this final leg he will be joined by Frank Skinner, Dermot O'Leary and Robbie Savage.
Bishop, 45, said: ‘I must be mad. I'm a man in my mid-40s, a bit thicker round the middle than I'd like to be and I'm about to take on the biggest physical challenge of my life.
‘Up until a few weeks ago I'd never even sat in a rowing boat and now I've got miles of water to cover, then there's the cycle and don't even mention the word marathon to me.
‘I know there will be times during the challenge when I'll be freezing cold and fed up but when I'm down I will think back to the people I met in Sierra Leone earlier this year and I'll know every penny I raise really will make a massive difference to people's lives.’
Bishop’s challenge will be filmed for a BBC documentary, to be broadcast in March.