Sabastian Sawe's time was not only a world record; he also became the first person to run an official marathon in under two hours.
The previous world record was held by Kelvin Kiptum, also from Kenya, at two hours and 35 seconds.
The runner-up in the race, Ethiopia's Yomif Kejelcha, also ran under two hours - in his marathon debut. He clocked 1:59:41.
Sawe, who won the London Marathon last year and has also run the Berlin Marathon, said that in the warm-up he felt he could run under two hours.
I'm so happy. This is a day to remember for me, said the 31-year-old.
The London Marathon is one of the world's most popular, with around 56,000 people participating last year.
