James closed with a 4-under 68 to finish at 15-under-par 201. The victory was James' third on the Champions Tour, but first since the 2005 Ace Group Classic.
Jay Haas, who shared the lead entering the final round with James and Craig Stadler, managed a 2-under 70 and finished alone in second at minus-13.
Brad Bryant (69), Morris Hatalsky (70) and R.W. Eaks (68) shared third place at 12-under-par 204.
Stadler stumbled down the stretch with a pair of double bogeys in the last four holes. He shot 2-over 74 and tumbled into a share of 15th.
Things remained tight over the first eight holes. James and Stadler birdied the second to pull one clear of Haas. A birdie on the third gave Haas a share of the lead at 12-under.
James and Haas each birdied the fourth, but Stadler again grabbed a piece of the lead with a 7-foot birdie putt on the sixth. All three players birdied the short par-4 seventh on The Old Course at Broken Sound Club.
That would be the final time there was a tie for the lead. James rolled in a 5-footer for birdie on eight to get to 15 under. James, as well as his playing partners Stadler and Haas, bogeyed the difficult ninth. That was the first bogey of the week for James.
Haas dropped another stroke on 10 to slip two back of James.
James drained a 16-foot birdie putt on 11 and a 5-foot putt for birdie on 12 to move to 16-under. At that point, James was three clear of Haas, who birdied 11 and bogeyed 12.
The 53-year-old James three-putted for bogey at the 14th, but was still three clear of Haas. James closed with four straight pars for the win.
'I tend to make birdies from the few wedges that I had so it wasn't a huge factor,' said James of his reaction to other players' bogeys. 'All week I've been trying to play pretty safe since there is so much water on this course.'
Haas fell four back with a bogey at 15, but took second place thanks to birdies on 16 and 18.
Loren Roberts fired a closing 67 to move into a share of sixth place at 11-under-par 205. He was joined there by Keith Fergus and Dana Quigley.
Andy Bean, Allen Doyle, David Eger, Scott Hoch, Mike Reid and Des Smyth tied for ninth at minus-10. Stadler ended alongside Vicente Fernandez at 9-under-par 207.