Thomas turned professional in 2013, deciding to forgo his final two years of college, and earned his tour card on the Web.com Tour through
qualifying school. He won his first professional event at the
2014 Nationwide Children's Hospital Championship. Thomas finished fifth in the 2014 Web.com Tour regular season, and third after the
Web.com Tour Finals, and earned his PGA Tour card for the
2015 season. In 2015, Thomas collected seven top-10s and 15 top-25s, with fourth-place finishes at the
Quicken Loans National and
Sanderson Farms Championship as his best results. He finished 32nd at the PGA Tour's FedEx Cup, losing the Rookie of the Year award to
Daniel Berger. On November 1, 2015, Thomas earned his first victory on the PGA Tour by winning the
CIMB Classic in
Kuala Lumpur, Malaysia, by a single stroke over
Adam Scott. He overcame a double bogey on the 14th hole during the final round and holed a six-foot (1.8 m) par putt to claim the win by a stroke. Thomas had earlier shot a course-record 61 during the second round to contribute to a 26-under-par winning score.
2016–17 PGA Tour: five wins, first major, FedEx Cup champion, Player of the Year Thomas successfully defended his title at the CIMB Classic in October
2016 for his second tour win. Thomas won the
SBS Tournament of Champions in January 2017 for his third PGA Tour win. In the following week's tournament, the
Sony Open in Hawaii, Thomas became the seventh player in PGA Tour history to shoot a
59. During the first round, he opened his round with an
eagle and needed to make an eagle on the ninth, his last hole of the day, to shoot 59. He became the youngest player to shoot a sub-60 round. Thomas finished with rounds of 64, 65, and 65 to win the tournament by 7 strokes. He set tournament records for 18, 36, 54, and 72 holes (59, 123, 188, and 253, respectively). He set PGA Tour records at 36 and 72 holes and tied the 54-hole record. During the third round of the
2017 U.S. Open at
Erin Hills, Thomas equalled the U.S. Open single-round record of 63. He eagled the last hole by hitting his 3-wood to 8 feet on the par-5 hole to finish at 9-under-par, also a U.S. Open record, passing the previous record held by
Johnny Miller at
Oakmont Country Club. In the fourth round, he played alongside
Brian Harman in the final grouping, the first time he had done that in a major championship. He shot a three-over-par 75 and finished in a tie for ninth place. In August 2017, Thomas won his first major, the
2017 PGA Championship, winning by two shots. At the
Dell Technologies Championship, Thomas became just the fourth golfer to win five times, including a major, in a PGA Tour season since 1960 before his 25th birthday, joining
Jack Nicklaus,
Tiger Woods, and
Jordan Spieth. After finishing runner-up to
Xander Schauffele at the
Tour Championship, Thomas became the
FedEx Cup champion on September 24, 2017.
2017–18 PGA Tour In October 2017, Thomas won the third event of the
2017–18 season, the
CJ Cup in South Korea. He defeated
Marc Leishman with a birdie on the second extra hole of a sudden-death playoff. The win was Thomas' seventh on the PGA Tour. In February 2018, Thomas won for the eighth time on tour, claiming victory at
The Honda Classic in
Palm Beach Gardens, Florida. He birdied the final hole of regulation play to make a playoff with
Luke List. Then on the first extra hole, Thomas made birdie again on the same hole, after a 5-wood from the fairway. List could not hole his birdie putt, after the missing the green to the right, resulting in Thomas winning the tournament. The win lifted Thomas to the top of the FedEx Cup standings and number three in world rankings. The following week, Thomas lost in a sudden-death playoff to
Phil Mickelson, at the
WGC-Mexico Championship. He had been even par for the tournament after the first two rounds, but then shot 62–64 over the weekend for a total of 16 under par. To finish his final round, Thomas holed his second shot to the 18th for eagle. Thomas lost the playoff to par, after going over the back of the green in the first extra hole and failing to up and down for par. Thomas moved to number two in the world rankings, a career best ranking. Thomas had another chance to claim the top spot in the world later on in March at the
WGC-Match Play, but he was beaten 3 & 2 by
Bubba Watson in the semi-finals. He then went on to lose the consolation match 5 & 3 to
Alex Norén to finish in fourth place. The result extended his lead at the top of the FedEx Cup standings and reduced the gap on the world number one,
Dustin Johnson. After the
2018 Players Championship, Thomas replaced Johnson as the world number one golfer. He lost that ranking after four weeks when Johnson won the
FedEx St. Jude Classic. In September 2018, Thomas qualified for the U.S. team participating in the
2018 Ryder Cup. Europe defeated the U.S. team 17 1/2 to 10 1/2. Notwithstanding the loss, Thomas went 4–1–0. He won his singles match against
Rory McIlroy.
2018–19 PGA Tour . On February 17, 2019, Thomas led the
Genesis Open entering the final round. Gusty conditions led to Thomas shooting 75 and finishing second to champion
J. B. Holmes. At one point, Thomas four-putted for a double bogey, the last three putts were inside 8 feet and the final miss was from 2 feet. On August 18, 2019, Thomas shot 25-under-par and won the
BMW Championship at
Medinah Country Club outside of Chicago. This was the second leg of the three-tournament
2019 FedEx Cup Playoffs and put Thomas in the lead in the FedEx Cup standings heading into the
Tour Championship at
East Lake Golf Club.
2019–20 PGA Tour On October 20, 2019, Thomas won the
CJ Cup in South Korea. This was his second win of the tournament in its three-year existence. In December 2019, Thomas played on the U.S. team at the
2019 Presidents Cup at
Royal Melbourne Golf Club in Australia. The U.S. team won 16–14. Thomas went 3–1–1 and lost his Sunday singles match against
Cameron Smith. On January 5, 2020, Thomas won the
Sentry Tournament of Champions at
Kapalua Resort in Maui, Hawaii for the second time. Thomas won in a playoff over
Xander Schauffele and
Patrick Reed. On August 2, 2020, Thomas won the
WGC-FedEx St. Jude Invitational at
TPC Southwind in Tennessee by three strokes over four other players. This was the second time that Thomas had won the event and his 13th career victory on the PGA Tour. He came from four strokes behind overnight leader
Brendon Todd to prevail on the final day. The win took Thomas to Number One in the Official World Golf Ranking for the second time in his career.
2020–21 PGA Tour On January 9, 2021, during the third round of the
Sentry Tournament of Champions in Hawaii, Thomas drew criticism for using a homophobic slur to express anger over a missed putt. Despite Thomas expressing contrition over the incident, describing his language as "inexcusable", sponsors
Ralph Lauren and
Woodford Reserve ended their relationships with him. In March 2021, Thomas shot a final round four-under par 68 to win the
2021 Players Championship by one stroke over
Lee Westwood. In September 2021, Thomas played on the U.S. team in the
2021 Ryder Cup at
Whistling Straits in
Kohler, Wisconsin. The U.S. team won 19–9 and Thomas went 2–1–1 and won his Sunday singles match against
Tyrrell Hatton.
2021–22 PGA Tour: one win, second major For the 2021–22 season, Thomas employed
Jim "Bones" Mackay to replace his previous caddie, Jimmy Johnson. The last round of golf Johnson caddied for Thomas was at the
2021 Ryder Cup. Mackay stepped into the role at the
CJ Cup. On May 22, 2022, Thomas won his second major and second
PGA Championship, defeating
Will Zalatoris in a playoff, overcoming a PGA Championship record 7-shot deficit entering the day.
2022–23 PGA Tour Thomas qualified for the U.S. team at the
2022 Presidents Cup; he won all four matches paired with
Jordan Spieth but lost in the singles. In September 2023, Thomas played on the U.S. team in the
2023 Ryder Cup at
Marco Simone Golf and Country Club in
Guidonia,
Rome,
Italy. The European team won 16.5–11.5 and Thomas went 1–2–1 including a win in his Sunday singles match against
Sepp Straka. In November 2023, Thomas competed in the inaugural
Netflix Cup, streamed as Netflix's first live sports broadcast. Thomas and
Formula 1 driver
Carlos Sainz Jr. played as a team, with the pair winning the event after Thomas won the "Closest to the Pin" style playoff, following 8 holes of scramble-format competition.
2025 PGA Tour In April 2025, Thomas won the
RBC Heritage in a playoff against
Andrew Novak. Thomas made a birdie putt from outside 20 feet to win for the first time since the 2022 PGA Championship. In round one, Thomas shot a 10-under 61 to tie the
Harbour Town Golf Links record. ==Personal life==