The men's 100 metres event at the 2020 Summer Olympics took place on 31 July and 1 August 2021 at the Olympic Stadium. 84 athletes were expected to compete; 27 nations used universality places to enter athletes in addition to the 56 qualifying through standard time or ranking. 78 athletes from 59 nations competed. Marcell Jacobs won the gold medal, establishing twice, semifinal and final, the new European record, Italy's first medal in the men's 100 metres. The United States extended its podium streak in the event to six Games with Fred Kerley's silver, only third at the U.S. Trials. Canadian Andre De Grasse won his second consecutive bronze medal in the 100 metres establishing his personal best. With Usain Bolt retired, Jamaica's three-Games gold medal streak ended.

Fredrick Lee Kerley is an American professional track and field sprinter who started his career competing in the 400 meters until 2020, when he transitioned to the 100 meters and 200 meters. He has earned several medals at the World Championships in the 400 m and 4 × 400 m relay including an individual bronze and a relay gold at the 2019 edition. Kerley claimed 100 m gold in the 2022 edition.