At the 2012 Summer Olympics in London, Grevers won a total of three medals: two golds and one silver. Grevers earned his first medal, a silver, by swimming for the second-place U.S. team in the preliminary heats of the 4×100-meter freestyle relay. In the final, the American team finished second behind France. Teaming with Jimmy Feigen, Ricky Berens, and Jason Lezak in the heats, Grevers swam the second leg and recorded a time of 47.59. After leading the heats (52.92) and semi-finals (52.66) of the 100-meter backstroke, Grevers won gold in the final of the 100-meter backstroke with a time of 52.16, bettering Aaron Peirsol's Olympic record of 52.54 set in 2008 and 0.76 seconds ahead of Nick Thoman. For Grevers, it was his first individual gold medal. In his final event, the 4×100-meter medley relay, Grevers won gold with Brendan Hansen, Michael Phelps and Nathan Adrian. Swimming the backstroke leg, Grevers recorded a time of 52.58 seconds, and the U.S. team went on to win with a time of 3:29.35.