The German two-putted for par from 50 feet on the 18th to finish at 12-under 204, surviving three bogeys and a double bogey to finish one stroke ahead of Jay Don Blake at TwinEagles' Talon Course.
The winner in 2011 and the runner-up last year, Langer earned his 17th victory on the tour. It's the seventh year the 55-year-old has won at least one tournament on the tour.
"I'm certainly relieved now, having won," Langer said. "It was definitely a grind. I was hoping to come down to the last hole with, whatever, a three-shot lead or something, make it easy."
Blake's 20-foot birdie putt on the 18th looked like it had a chance until the last few feet, when it turned and grazed the edge of the cup.
"I actually thought I had made it, gave it a good effort, but just wasn't good enough," said Blake, who was playing ahead of Langer in the next-to-last group.
Tom Pernice Jr. tied for third with John Cook, who birdied Nos. 16 and 18 for a 68 that left him at 9-under 207. David Frost and Rocco Mediate, a Calusa Pines Golf Club member, tied for fifth at 8-under.
After leading by four early in the round, Langer double-bogeyed No. 4, and later missed a 2½-foot par putt on No. 10 for his second straight bogey to fall into a tie with Blake and Pernice.
Blake, who birdied four holes on the front nine, took the lead briefly with a two-putt birdie on the par-5 13th to get to 12 under. But Langer, playing in the group behind Blake, also birdied the hole, and added another on No. 14 to take the lead again.
Langer had switched up his putting grip after leaving a birdie putt short on No. 11.
"I made some better strokes that way, and made some decent putts there towards the end," he said.
Blake missed a 3-footer for par on No. 16, and Langer bogeyed No. 15, keeping Langer a stroke ahead. But the bogey could have been worse. Langer's tee shot ended up in a bad lie 95 yards from the green. He hit his second shot fat, and went in the water short of the green. After taking a drop, Langer hit a lob wedge to 5 feet.
"(I) made that for a great bogey," he said.
Langer's even-par 72 matched the highest final-round score for a winner at the ACE. Craig Stadler also shot a 72 in 2004. Both Langer and Stadler survived double bogeys to win. Langer won $240,000 out of the $1.6 million purse.
Pernice bogeyed No. 11, then missed a short birdie putt at No. 12 and couldn't recover. Down two strokes, he went for the green on the par-5 17th in two, hooked a 3-wood into the water and made bogey.
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