Gangloff represented the United States at two consecutive Summer Olympics. At the 2004 Summer Olympics in Athens, he earned a gold medal by swimming for the winning U.S. team in the preliminary heats of the 4×100-meter medley relay. In individual competition, he placed fourth in the men's 100-meter breaststroke. Four years later at the 2008 Summer Olympics in Beijing, he again participated in his signature event, the 100-meter breaststroke, and placed eighth in the event final.