Previously, he won a silver medal as a member of the second-place U.S. team in the 4×100-meter freestyle relay at the 2012 Summer Olympics.

[2] On the morning of August 14, teammate Ryan Lochte claimed that he, Feigen, Gunnar Bentz, and Jack Conger were robbed after four men forced them out of their taxi at gunpoint.

[4] Civil Police of Rio de Janeiro concluded that the athletes were not robbed, but instead had been involved in an incident at a gas station in Barra da Tijuca, west of the city.

[1] They also claimed that the swimmers had already paid in cash 100 reais ($31) and $20 in U.S. currency as compensation for objects from the bathroom which were damaged, such as a soap holder, a mirror, and a "Please Do Not Enter" sign.

[10] This report by the Rio Police department was subsequently refuted through witness statements as well as a USA Today article which found no such vandalism ever occurred.

[12] The Associated Press reported that Conger and Bentz "refuted Lochte's claim that the group was held up by armed assailants.

[23] In the 4×100-meter medley relay, Fiegen earned a silver medal with Rex Tullius, George Klein, and Tim Phillips.

Teaming with Matt Grevers, Ricky Berens and Jason Lezak, Feigen swam the lead off leg and recorded a time of 48.49 seconds.

In his first event at the World Championships, Feigen combined with Nathan Adrian, Ryan Lochte, and Anthony Ervin in the 4×100-meter freestyle relay, with the team finishing behind France.

Feigen competed in the 2016 Summer Olympics, winning a gold medal by swimming in the preliminary rounds of the Men's 4x100 meter freestyle relay.