The men's single sculls event was part of the rowing programme at the 1920 Summer Olympics.

In the final, Kelly defeated Great Britain's Jack Beresford in "of the greatest sculling races ever contested.

"[2] Beresford led most of the way, with Kelly passing him late and winning by one second—a very close race in single sculls.

John B. Kelly Sr. and Jack Beresford are cited as the best scullers to have ever come from the United States and Great Britain, respectively.

Kelly had been excluded from the Diamond Challenge Sculls in 1920, primarily due to a ban on the Vesper Boat Club to which he belonged, though his work as a bricklayer was also cited as a violation of amateurism rules.