Fitzpatrick won the 2012 Boys Amateur Championship at Notts Golf Club (Hollinwell). He made the cut at the 2013 Open Championship and finished as low amateur, winning The Silver Medal. Fitzpatrick and Jimmy Mullen were the only amateurs to make the cut, with Fitzpatrick finishing on 294 to Mullen's 299. Later in 2013, Fitzpatrick won the U.S. Amateur, which earned him invitations to the 2014 Masters Tournament, U.S. Open, and Open Championship provided he remained an amateur. The U.S. Amateur win took him to the top of the World Amateur Golf Ranking which earned him the Mark H. McCormack Medal. In September 2013 he played in the Walker Cup.