'I missed a couple of good opportunities, but I made the saves when I needed to and that's what kept my nose out in front,' said Scott, who earned $864,000 for the win. 'It would have been a real tough feeling if I got reeled in today.'
Charles Howell III, who fought within two strokes of Scott during the final round, ended alone in second place at 17-under-par 267 after a closing 65.
Rory Sabbatini, the 2003 champion, finished alone in third place at 15-under- par 269. Tim Herron, Arron Oberholser and Bo Van Pelt shared fourth place at minus-12.
Scott stumbled to a bogey at the second, but quickly made up for that mistake. The young Australian dropped in a birdie at the third and came right back with a birdie at the fourth to get to 19 under.
He made it three in a row with a birdie at the fifh. Prior to a bogey at the ninth, Scott's lead grew as high as seven shots.
Howell opened with back-to-back birdies from first to get to 13 under. After eight straight pars, Howell put together a great run of golf to close in on Scott.
Howell ran home five consecutive birdies from the 11th at the TPC at Avenel to move to 18 under par.
Scott, meanwhile, had parred four holes in a row before dropping in a birdie try at the 14th to stay two shots clear of Howell. Scott made it two straight with a birdie at the 15th to inch three shots ahead of Howell.
Both players parred the par-4 16th, before the final turning point at the 17th. Howell faltered to a bogey to fall back to minus-17.
Scott, going for his second win of the season, birdied the same hole to move five shots clear of Howell at 22 under. Scott, who won the Players Championship earlier this year, tripped to a bogey at the last, but no matter, the win was his.
He now owns three PGA Tour titles, all coming on TPC venues - Boston, Avenel and Sawgrass.
'I really just focused on speed this week,' said Scott of his putting stroke. 'I guess my tendency is to get technical and I just let all that go and just try to putt with what ever feels comfortable. I found a pretty good speed this week.'
Howell picked up his third top-10 of the season and his fifth career runner-up finish.
'Adam's a great player. It got close there for a little bit today, but he made the birdies when he had to,' said Howell. 'I've been working awfully hard on my game with my coach, David Leadbetter. We've spent a lot of time together and I'm fortunate to have him around.'
Olin Browne and Alex Cejka shared seventh place at 11-under-par 273. Aaron Barber and Frank Lickliter, the 2001 champion, ended one stroke further back at minus-10.
Harrison Frazar, Tom Lehman, Ryan Palmer, Jeff Sluman and Duffy Waldorf, who shared second place here last year, tied for 11th place at nine-under-par 275.