Harrington claimed the win in Bermuda despite a course-record-tying round from Webb Simpson.
Padraig Harrington held off a charging Webb Simpson to win the 2012 PGA Grand Slam of Golf event on Wednesday in Southampton, Bermuda.
Harrington hit home consecutive birdies on holes 11, 12 and 13 to take a four-shot lead on Simpson, who made a charge but eventually fell a shot short. Harrington's four-under 67 left him at nine-under par for the tournament win.
Simpson shot a six-under 65 on Wednesday, tying the course record for Port Royal Golf Course in Bermuda.
Keegan Bradley finished third with a 67 on Wednesday, making up for his first round of 72, the only over-par result of any round in the two-round event. That tied him for third at three under with Bubba Watson, who shot an even 71 on Wednesday.
The event matched up the winners of the four major tournaments of the year. Harrington became a part of the field when British Open champion Ernie Els withdrew, while Bradley returned to the event when PGA Champion Rory McIlroy withdrew.
Here are the purse winnings for the four golfers:
Padraig Harrington: $600,000
Webb Simpson: $300,000
Keegan Bradley: $225,000
Bubba Watson: $225,000