Affectionately nicknamed “Dumbo” by her legion of fans (Flying Dumbos), Chun introduced herself to the golf world with a final-round 66 for a one-stroke victory over countrywoman Amy Yang in the 2015 U.S. Women’s Open at Lancaster (Pa.) Country Club. Chun later returned to Lancaster to establish the In Gee Chun Educational Foundation. Also in 2015, Chun became the first player to win major championships on three different circuits. Besides her Women’s Open victory, she won majors on both the Korean LPGA Tour and Japan LPGA Tour. Chun captured her second major title at the 2016 Evian Championship with a 21-under total of 263, and then claimed her third at the 2022 KPMG Women's PGA Championship at Congressional Country Club. Ten of her 14 worldwide victories have come on the KLPGA.