The kitchen guru was part of Virgin entrepreneur Richard Branson's all-star team aiming to complete the 26.2-mile (42.2-kilometre) run across the U.K. capital.
But Ramsay didn't reach the finish line with his groupmates - he pulled out of the race part-way through due to injury.
Branson says, "Even the best marathon runners drop out. You can get cramp so easily. I don't think anybody should feel disappointed or ashamed. At least he tried."
Runners in Branson's team who completed the gruelling race included Australian singer Natalie Imbruglia and British royal Princess Beatrice.