Devitt became the first Australian to win an Olympic gold medal in the 100m freestyle, but his victory at the 1960 Olympic Games in Rome was controversial.

Devitt was awarded the gold medal despite the timekeepers recording a slower time than the American silver medallist, Lance Larson. At that time, Olympic results were decided by nine judges, and two of the three first-place judges chose Devitt as the winner, while two of the three second-place judges determined Devitt as the second-place finisher behind Larson.

A new timing machine was used at the Rome 1960 Olympic Games, but it was not considered to be reliable. Therefore, despite the timing machine clocking Larson at 55.10 and Devitt at 55.16, chief judge Hans Runstromer overruled in favour of Devitt and awarded him the gold medal. The USA appealed three times over the next four years, but the appeals were all rejected.

The incident led to the introduction of automatic timing, which has been in place at all international meets since the 1968 Olympic Games in Mexico City.

Devitt also won the 4x200m freestyle relay bronze in Rome before retiring from swimming after the 1960 Olympic Games. He went on to have a successful career in business and was also involved in the administration of swimming, serving as the President of Swimming Australia from 2000 to 2004.

Devitt was inducted into the International Swimming Hall of Fame in 1979.