The men's Keirin at the 2008 Summer Olympics took place on August 16 at the Laoshan Velodrome.

The first 5.5 laps were behind a motorized pacer called a derny, which gradually increased speed up to 50 km/h (31 mph; 14 m/s).

The derny then left the track and the cyclists then raced the final 2+1⁄2 laps to the finish.

The top three cyclists in each semifinal advanced to the final, while the bottom three competed in the 7th to 12th place classification race.

Chris Hoy (Great Britain) qualified directly by winning the Keirin at the 2008 UCI Track Cycling World Championships.