The Ryder Cup star led by two strokes at the start of the day and after holding off an early charge from Scott Stallings, he pulled clear with six birdies on the day.
The 34-year-old birdied the first and also all four par 5s at the Dublin, Ohio resort as he closed with a four-under-par round of 68 for a 12-under total of 276. Playing partners Kevin Chappell and Kyle Stanley were second and third on ten under and seven under respectively.
“It’s such an amazing feeling, this stuff never gets old,” Kuchar said after being congratulated by tournament host Jack Nicklaus. “To win this and have Jack Nicklaus congratulate me is a real treat.”
Kuchar extended his lead over playing partners Kyle Stanley and Kevin Chappell at the first opportunity and it soon appeared the challenge would come from a surprising source.
Stallings, who looked to have dropped well out of contention with a round of 75 on Saturday, played the front nine in five under par with a run of five successive birdies from the fourth hole. And when another followed at the 10th he was alone in second on seven under par, two shots behind Kuchar.
That was as good as it got, though, and another birdie at the 17th was sandwiched by bogeys. Kuchar gave his opening birdie back at the par-three fourth but was on in two at the par-five next. His eagle putt ran just through but he tapped in for birdie to go to nine under.
The long seventh and 11th brought further birdies and he repeated the trick at the 15th.
He bogeyed the 16th and found a fairway bunker at the next, but escaped safely to the middle of the green and birdied the last with no alarms, rolling in a nice right-to-left putt from 21 feet. The first prize of $1,116,000(£734,000) adds to significant paydays for his wins over the past three years – The Barclays in 2010, last year’s Players Championship and the World Golf Championships-Accenture Match Play Championship earlier this season.
The latter means only he and Tiger Woods have more than one event on tour this season. World No 1 Woods was a long way off the pace here, eight over after a level-par closing round to follow his nightmare 79 on Saturday. Chappell was steady through the first 12 holes but failed to make a move, notably at the friendly par fives which served Kuchar so well.
He birdied the 13th and 15th, the latter after a tee-shot sent flush over the pin, to keep himself in contention.
Stanley’s challenge sputtered out at the 17th as he hit his second shot from one bunker to another, was unable to splash out on to the green and then underhit his chip, before holing a good putt to escape with bogey.
Chappell holed a good 19-foot birdie putt to go down the last hole two strokes behind the leader, hit his approach just a couple of feet short of the pin and made birdied but to no avail.
Stallings shared fourth place with Bill Haas on six under, with Australia’s Matt Jones the leading non-American in a share of sixth. English pair Justin Rose, the 2010 champion, and Brian Davis were four under along with 2011 Masters champion Charl Schwartzel.