At the 2012 Summer Olympics in London, she turned in a personal best time of 57.42 seconds during the semi-finals of the 100-meter butterfly and advanced to the finals. In the finals, she swam the race in 57.48 en route to a seventh-place finish. "My goal was actually just to get in the finals, and once I got that it was just kind of icing on the cake being able to compete in the finals", she remarked. "So I'm thrilled. I'm so happy with how I've done." Later at the games, she swam the butterfly leg of the 4×100-meter medley relay for the U.S. team during the preliminary heats. Her teammates won the relay final, earning Donahue a gold medal.