At the 2016 Summer Olympics, Sun won a gold medal in the 200 metre freestyle and a silver medal in the 400 metre freestyle. By winning the 200 metre freestyle, he became the first swimmer in history to win Olympic gold medals in the 200, 400, and 1500 metre freestyle events. At the 2017 World Championships, he won his first world title in the 200 metre freestyle, setting a new Asian record. In 2018, Sun won gold medals in every freestyle event (200, 400, 800, and 1500 metres) at the Asian Games, as well as silver medals in two relay events. In 2019, he successfully defended his titles in the 200 and 400 metre freestyle events at the World Championships. He won his fourth consecutive title in the 400 metre freestyle, the first and the only swimmer to do so. As of 2021, Sun Yang's 1500 metre world record remains the only Men's Individual Freestyle long course world record achieved without the use of the high-tech swimwear that controversially dominated swimming victories and records in the 2008-09 seasons.