David Walliams said completing his 140-mile charity swim along the River Thames would be "meaningless" without supporters who donated more than £1 million.
Thousands of fans gathered at Westminster Bridge to cheer as the funnyman, who was brought up in Banstead, finished his gruelling eight-day journey.
Afterwards, he joked: "I think a bath is the only water I want to see for quite a while."
Among those who welcomed him were his wife Lara Stone, comedian and actor Lenny Henry, actress Barbara Windsor, comic Miranda Hart and Olympic rower Steve Redgrave.
When asked by Henry what he would like to say to his supporters, he said: "Thank you so much, thank you for your waves, your cheers, but most of all thank you for your donations, because each time this would be completely meaningless unless you all put your hands in your pocket, and I know times are hard so I really, really thank you from the heart, you're really going to make people's lives better."
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