The men's marathon 10 kilometre event at the 2020 Summer Olympics was held on 5 August 2021 at the Odaiba Marine Park.

Florian Wellbrock won the gold medal for Germany, with a final time of 1:48:33.7.

This was 25.3 seconds ahead of silver medalist Kristóf Rasovszky of Hungary; Gregorio Paltrinieri of Italy took the bronze.

[5] This was the first time anybody had won the men's 10 kilometer event at the Olympics by breaking away at the start and holding the lead until the finish.

[5] The men's 10 km open water marathon at the 2020 Olympics featured a field of 25 swimmers:[6] Unlike all of the other swimming events in the pool, the men's and women's marathon 10 kilometre races are held in open water.