On the same day of his 50 m butterfly gold, Phillips then competed in the 4x100 m freestyle relay with Jimmy Feigen, Kohlton Norys, and Robert Savulich.

[1] In the 100 m butterfly, Phillips won the gold ahead of compatriot Tom Shields in a time of 52.06, becoming the first American man to win the event since 1995.

[2] In the 4x100 m medley relay, Phillips earned a silver medal with Rex Tullius, George Klein, and Jimmy Feigen.

At the 2015 World Aquatics Championships held in Kazan, Russia, Phillips swam the butterfly leg of the 4x100 m medley relay in the qualifying heat.

Even though he did not swim in the event final for the winning U.S. relay team, Phillips earned a gold medal for his participation in the qualifying race.