The comedian vowed to make the 290-mile journey from Paris to London in just five days to raise money for charity. He admitted that he was "so tired" while completing the Channel part of the task alongside Davina McCall, Andrew 'Freddie' Flintoff and Denise Lewis, as he had already cycled 185 miles the previous day.
Bishop said: "Yesterday's cycle was so difficult and long that it made the row today even harder than it already was. I was so tired out there that I actually fell asleep while I was rowing.
"I'd nod off for a split second, wake up and see two oars in the water. I was delirious after just having a single hour of sleep the night before - but that's why it's called the 'Week of Hell'.
"I couldn't have picked a better trio to help me do it, they were amazing and never ever looked like stopping."
McCall added: "That seemed to just go on and on. Our cox told us at the start that we'd be doing something like 10,000 strokes and it really felt like it.
"I've absolutely no idea how John did it. To row the channel after cycling almost 200 miles and only having one hour of sleep in between is astonishing."
Bishop, who will now complete his triathlon with a run to London, has previously revealed that he hopes to raise enough money to pay for a vaccine against five deadly diseases for 250,000 children in Africa and also to help people experiencing hardship in the UK.
Sponsor John Bishop on his 'Week of Hell' by visiting http://www.sportrelief.com/whats-on/celebrity-challenges/bishops-week-of-hell.
> John Bishop suffers bike fall on Sport Relief 'Week of Hell' - video
> John Bishop Sport Relief triathlon back on after French rowing ban
Take a look at pictures from John Bishop's Sport Relief challenge below: