In a tight duel with Sergio Garcia for the entire round Sunday at PGA National, Scott stayed out of the water and closed with an even-par 70 for a one-shot victory. It was his first title since Colonial in May 2014, and his first time winning with a conventional putter since the 2010 Singapore Open.
The timing of his victory also was a big statement for the 35-year-old Australian.
Scott won in just his third start since a new rule took effect that bans the anchored stroke typically used for the long putter that he had the past five years. Scott switched back for good at the Presidents Cup. This was his 10th start since then, and only twice has he finished out of the top 10.
Scott opened with a 10-foot birdie that settled him and led by no more than two shots until back-to-back bogeys around the turn. But it was a two-man race all day, and Scott seized control when Garcia missed a short par putt on No. 11 and Scott hit a fairway bunker shot to 2 feet for birdie on the next hole.
Unlike Saturday, when Scott took a quadruple bogey on the par-3 15th with two shots into the water, he stayed dry around the treacherous finish at PGA National.
The only nervous moment was on the 16th hole when Scott had a one-shot lead.
Garcia hit a poor pitch and was headed for a bogey. Scott left his 40-foot birdie attempt 10 feet short, and the par putt stopped short of the hole to keep the margin at one heading to the raucous 17th, a par 3 over the water.
Scott's 7-iron covered the flag, and it was no small relief for him when he saw it hit the green. Garcia made another bogey, and Scott had a two-shot lead going to the 18th, where a par was enough for him to win for the 12th official time on the PGA Tour.
''I hit a lot of good putts that didn't go in. Fortunately, it was enough at the end,'' he said.
Scott finished at 9-under 271 and moved to No. 9 in the world, his highest ranking in 10 months.
''He played really, really solid,'' Garcia said. ''I played with him the last two days, and he looked awesome. I know I can play better. That's the good thing. Without feeling like I was swinging that great, I still managed to have a chance, so I'm happy with that.''
Justin Thomas closed with a 69 and tied for third with Blayne Barber (70), four shots behind. Graeme McDowell had a 69 to finish another shot behind, while Rickie Fowler lost momentum on the back nine for a 71 and joined Vijay Singh at 3-under 277.
Scott appeared to be in control until failing to save par from a bunker on No. 9 and a wild tee shot on the 10th. But on one of the more daunting shots over water on the course, he fired at the right pin at the 11th. Scott narrowly missed the birdie putt, though it seemed to steady him.
He got through the late par 3s over water - Nos. 15 and 17 - without trouble, even if there were a few moments that made him pause. He was set up over his shot on the 15th when a small puff of wind in his face was all it took to make him back off.
The day before, Scott was leading by three shots when he made a 7 on the hole and lost the lead. This time, he settled himself and hit a safe shot to 30 feet, and Garcia looked back at him and said, ''Good shot.''
That turned out to be the only big blemish on what otherwise had been a flawless display from one of the prettiest swings in golf. The victory proved to be validation that he can still get around with a short putter. Scott won 18 times around the world with a short putter, including The Players Championship and the Tour Championship.
He switched to a long putter that he anchored to his chest at the 2011 Match Play Championship, and contended at the Masters two months later. Scott won seven times with the long putter, including the Masters in 2013 when he was the fourth winner in the six majors to use an anchored putting stroke.
DIVOTS: Scott's victory bumped Jason Dufner out of the Cadillac Championship next week at Doral. The top 10 in the FedEx Cup standings are eligible for Doral, and Dufner had been No. 10 going into the Honda Classic. ... Scott now has gone 18 straight rounds at par or better.