Triathlon at the 2012 Summer Olympics – Men's

The men's triathlon was one of the triathlon events at the 2012 Summer Olympics in London, United Kingdom. It took place on 7 August 2012, featuring 55 men from 32 countries. It was the fourth appearance of an Olympic men's triathlon event since the first at the 2000 Olympics in Sydney. The race was around Hyde Park, a 1.42 km² park in central London. The race was held over the "international distance" (also called "Olympic distance") and consisted of 1.5 kilometres (0.93 mi) swimming, 42.959 kilometres (26.693 mi) road cycling, and 10 kilometres (6.2 mi) road running.

A group of six finished the 1,500 metres (1,600 yd) swim leg in a lead group. Great Britain's Jonny Brownlee was given a 15-second penalty for an illegal transition between the swimming and cycling disciplines. A large lead group was together at the end of the cycling leg but Jonny Brownlee's brother Alistair Brownlee (Great Britain) broke away on the run to win the gold medal with Spain's Javier Gómez in second and Jonny Brownlee in third. Alistair Brownlee earned Great Britain's nineteenth gold medal at the 2012 Games.

Almost immediately after the race, bronze-medallist Jonny Brownlee collapsed due to heat stroke; it was confirmed he would suffer no permanent damage.