The men's 100 metre freestyle event at the 1980 Summer Olympics was held on 26 and 27 July at the Swimming Pool at the Olimpiysky Sports Complex.

The event was won by Jörg Woithe of East Germany, the nation's first medal in the men's 100 metre freestyle.

Sweden earned its first medals in the event since 1952 with Per Holmertz's silver and Per Johansson's bronze.

The top sprinters of the time were absent, Rowdy Gaines due to the American-led boycott and Jonty Skinner due to the ban on apartheid South Africa.

[2] Algeria, Angola, Cyprus, Libya, Madagascar, Mozambique, and Zimbabwe each made their debut in the event.