The 35-year-old, who recently won at New Orleans and was also married last weekend, landed a 25-yard putt on the 18th green after a stunning drive had seen him turn the pressure up on Pride.
He ended on 10-under par, seeing off Pride by a shot, and he told Sky Sports 1 afterwards: "We got bunched up at the top and I had a nice chance on 18th the close it out.
"For me, it the winning putt was right to left, and I had a really good feel for it."
Pride, without a win on the Tour, had kept himself in contention with a 40-foot putt on the penultimate hole, but he could not match his rival on the home straight.
Dufner, leader going into day three, had lost his way slightly by dropping two early shots, and lost the lead as JJ Henry landed a stunning hole in one on the par-three fifth.
Henry ended two shots behind Dufner, though, and one behind Pride, as one of four men on nine under, with the other three being Marc Leishmann, Joe Durant and Jonas Blixt.
There was then a three-shot buffer to the rest, with Phil Mickelson among them on six under.
He went around in four-under today but had left himself with too much to do, as had Ken Duke who ended on the same score.
Vijay Singh, so impressive yesterday, was one over for today and ended up six shots shy of Dufner, while Padraig Harrington was seven behind despite a one-under 69 today.
The round of the day went to Germany`s Alex Cejka, although his five-under 65 could only take him to one under for the tournament.