The 25-year-old American parred the second extra hole of a playoff against Alex Cejka and Whee Kim to win the Shriners Hospitals for Children Open at the TPC Summerlin in Las Vegas.
Cantlay claimed the title despite carding bogeys at his final two holes of regulation play.
A former World No. 1 amateur, Cantlay didn't play a single event on the PGA Tour in either 2015 or 2016 as he battled severe back problems.
In January 2016, Cantlay was out in California with his friend and former caddie, Chris Roth, the moment Roth was struck by a passing car.
Roth died later in hospital at the age of 24.
Cantlay's struggles have been well documented and his triumph in Las Vegas is the breakthrough moment which so many of the game's followers had thought was inevitable even long before he turned professional in 2012.
“It was a tough day towards the end but really easy at the start,” Cantlay said after his playoff win in Las Vegas. “I felt like I needed to go out there and make a bunch of birdies. I was trying to get to 12 or 13 under and I thought that would be close but with the wind coming in obviously it was a little different end to the tournament."
Cantlay has been a model of consistency since returning to the PGA Tour on a medical exemption at the Pebble Beach Pro-Am in February. He made a cheque in all 12 starts on the PGA Tour in 2017 and has continued on that trend in two starts in the new wrap-around schedule.
A bogey at the first playoff hole didn't derail Cantlay's title bid with Cejka and Kim also taking five on TPC Summerlin's difficult par-four 18th as it was buffeted by a strong cross wind.
On the second playoff hole, Cantlay's brilliant approach between two trees was too strong and rolled over the back of the green before he almost holed out with his putter from about 60 feet away.
Cantlay was left with a three-foot par putt for the title and he calmly converted.
Aaron Baddeley recovered from a third round of 74 to finish with 68 today and share 10th position, just his second top-10 of 2017.
Of the other Australians to make the weekend, defending champion Rod Pampling was 47th and Geoff Ogilvy 75th.
2017 PLAYER PROFILE: SERGIO GARCIA
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