Grevers finished in 52.16 seconds, 0.38 ahead of the previous mark set by fellow American Aaron Peirsol at the 2008 Beijing Games.
Nick Thoman, another American, was second in 52.92, and Ryosuke Irie of Japan was third in 52.97.
Grevers attended Chicago's Northwestern University and participated in the 2008 Beijing Games, where he won two relay gold medals and a silver in the 100, according to the Olympic website.
The Associated Press contributed to this story.
