The Little Britain star raised more than $1.6 million (£1 million) for Britain's Sport Relief this month (Sep11) by completing a gruelling endurance test along a 140-mile (225-kilometre) stretch of the River Thames in the U.K.
On Saturday (10Sep11) - day six of the challenge - Walliams spotted a Labrador struggling to stay afloat after jumping into the water, and he diverted from his intended course to save the drowning dog, named Vinnie.
Speaking after the drama, Walliams said, ""I heard a splash and looked over to be met with the face of a sweet Labrador. I thought he was fine, but he started to really struggle.""
Now bosses at PETA have announced they will present the funnyman with the organisation's Hero to Animals Award for his efforts.
A spokeswoman says, ""David's rescue of Vinnie shows that he is a hero to both people and animals! PETA hopes that his compassionate action will serve as an inspiration to others always to help animals in need.""