Homa was born in Burbank, California to John Homa and Bonnie Milstein. He graduated Valencia High School in 2009 and played college golf at University of California, Berkeley where he was a first-team All-American as a senior. In 2010, he reached the quarterfinals of the U.S. Amateur before losing to reigning champion and Cal teammate An Byeong-hun. Homa competed as an amateur at the 2013 U.S. Open and won the individual 2013 NCAA Division I Championship. He was selected to the 2013 U.S. Walker Cup squad and turned pro after the event.
In October 2013, Homa finished T-9 at the Frys.com Open, his first PGA Tour event as a pro. In December 2013, he tied for 6th place in the Web.com Tour qualifying school. In May 2014, he earned his first professional win at the Web.com Tour’s BMW Charity Pro-Am. He finished 17th on the Web.com Tour regular-season money list to earn his PGA Tour card for the 2014–15 season.
In the 2015 PGA Tour season, Homa entered 27 events. He made 12 cuts and won $380,339. He finished 163rd in the FedEx Cup standings and lost his tour card. In the 2016 Web.com Tour season, Homa won the Rust-Oleum Championship in Ivanhoe, Illinois, and ultimately regained his PGA Tour Card for the 2016–17 season. In the 2017 PGA Tour season, Homa made only two cuts in 17 events and lost his card. In the 2018 Web.com Tour season, Homa regained his PGA Tour card for the 2019 PGA Tour season.