The men's 100 metre breaststroke event at the 1988 Summer Olympics took place between 18–19 September at the Jamsil Indoor Swimming Pool in Seoul, South Korea.

[1] The winning margin was 0.01 seconds which as of 2023 remains the only time this event for men has been won at the Olympics by less than a tenth of a second.

Prior to this competition, the existing world and Olympic records were as follows.

Rule: The eight fastest swimmers advance to final A (Q), while the next eight to final B (q).

[2] * Opted to swim for the consolation final instead.