On November 12, 2017, Fowler started his 2018 season at the OHL Classic at Mayakoba where he shot rounds of 65-67-67-67 for an 18-under-par total, one stroke shy of winner, Patton Kizzire. It was his 12th tour runner-up finish and he became just the 27th golfer in PGA Tour history to win $30,000,000 in Tour earnings.
On December 3, 2017, Fowler recorded a 61, 11-under-par, in the fourth round to win the Hero World Challenge. He came from 7 strokes behind the 54-hole leader, Charley Hoffman and claimed a four-stroke victory. The round of 61 was a course and tournament record, as well as being a personal best round for Fowler as a professional.
Fowler started dating track and field amateur athlete Allison Stokke in 2017. They became engaged in June 2018. They married in October 2019.