In August 2020, DeChambeau briefly held a share of the lead during the final round of the PGA Championship; he went on to finish in a tie for fourth place, his first top-10 finish in a major championship. Six weeks later, at the 120th U.S. Open at Winged Foot, he came from two strokes behind at the start of the final round to win his first major championship. His six-under par total gave him a six stroke victory over Matthew Wolff. He was the only player under par in the final round, with a three-under par 67 and the only player to finish under par for the tournament. With the win, he became the third player in history, after Jack Nicklaus and Tiger Woods, to win the NCAA Individual Championship, the U.S. Amateur and the U.S. Open during a career. The win moved him to number five in the Official World Golf Ranking, matching his previous best, which he had first achieved in November 2018.