[2] The event was won by Usain Bolt of Jamaica, the first man to repeat as champion in the 200 metres.

Bolt's gold medal was Jamaica's third in the event, moving out of a tie with Canada and Italy for second-most overall (behind the United States' 17 wins).

Two of the eight finalists from the 2008 Games returned: gold medalist Usain Bolt of Jamaica, fifth-place finisher Christian Malcolm of Great Britain, and the two men who had finished second and third but been disqualified for stepping out of their lanes: Churandy Martina of the Netherlands Antilles and Wallace Spearmon of the United States.

Jesse Owens ran afoul of harsh amateurism rules after his 1936 win (and would have lost any opportunity to repeat with the outbreak of World War II in any case); Andy Stanfield lost by 0.22 seconds in 1956 after winning in 1952; Pietro Mennea made the final four times and came away with a gold and a bronze; Carl Lewis lost by 0.04 seconds in 1988 after winning in 1984; food poisoning robbed Michael Johnson of his first opportunity in 1992 before he won in 1996; Bolt himself had made Shawn Crawford the third gold-silver winner by beating him in 2008.

The United States, which had the winner in 5 of the last 7 appearances of the event, had no strong runner to challenge Bolt.

Usain Bolt dominated the second heat, jogging and looking around for non-existent challengers down the straight.

And in heat three, Warren Weir was running easily, easing up at the finish to let Churandy Martina take the first spot, knowing he had qualified in the second position.

Slowest qualifier Álex Quiñónez, racing hard for his 20.37, was on the opposite side of a clear dividing line in the field.

In the final, Bolt, who was in lane 7, moved past his Jamaican teammate Weir after only 50 metres; coming off the bend and onto the final 100-metre straight, Bolt's lead over the rest of the field had grown to several metres, however Blake began to pull him back.

Weir completed the 1–2–3 sweep for the Jamaicans by winning the bronze medal, the second time in any international competition that Jamaica has achieved this (after the women did it in the 2008 100 metres).