In 2013, Manassero won the biggest tournament of his career to date: the 2013 BMW PGA Championship with a birdie at the fourth extra hole of a playoff against Simon Khan and Marc Warren, becoming the youngest-ever winner of this tournament. With the win Manassero gained the right to play in the 2013 U.S. Open and entered the top 30 of the Official World Golf Ranking. He also managed to further improve his final Order of Merit position with an 11th place.