The Men's 81 kg Judo competition at the 2008 Summer Olympics was held on August 12 at the Beijing Science and Technology University Gymnasium.

This event was the median of the men's judo weight classes, limiting competitors to a maximum of 81 kilograms of body mass.

If the bout was still tied at the end, it was extended for another five-minute, sudden-death period; if neither judoka scored during that period, the match is decided by the judges.

The tournament bracket consisted of a single-elimination contest culminating in a gold medal match.

The two judokas who lost in the semifinals faced the winner of the opposite half of the bracket's repechage in bronze medal bouts.