The win moved Irwin past the $20 million mark in all-time career earnings, joining Tiger Woods as the only other player to reach that plateau. It is also the eighth straight year that Irwin has earned a Senior Tour win.
'It's been a great career,' he said. 'The entire career I've been very fortunate to be at the right place at the right time.
Irwin began the day two shots behind overnight leader Tom Watson in what became a head-to-head battle between the two golf legends.
The pair stepped onto the decisive par-5 17th tee. Irwin played first, hitting his drive into a fairway bunker. It was now a three-shot hole for Irwin, with Watson giving himself the opportunity to reach the green in two after a solid tee shot.
'I knew I couldn't get to the green in two,' said Irwin. 'After Tom really bombed his drive, I wanted him to go for that green. It's not an easy shot, he just didn't hit it the way he wanted to.'
Watson had 232 yards to clear the water in front of the green, but his fairway wood fell just short of the ledge before the putting surface. His fourth shot left him with a long par putt and opened the door for Irwin.
Irwin hit out of the bunker leaving a short approach. He landed his third shot 12 feet from the hole to set up a birdie while Watson made bogey for a two-shot swing.
'I had my opportunity at 17 and I hit it about 10 yards left from where I was trying to hit it,' said Watson. 'I was trying to put the pressure on Hale. He's back there in a safe position and I'm in a risky position right there and I didn't hit the risky shot very well.'
The lead was enough for Irwin to bogey the final hole as Watson managed only a par.
'It was like the old days out there,' said Watson. 'I've always admired the way he plays.'
'It just so happened two players with some fame or infamy were
battling it out,' said Irwin.
He made his first birdie on the third to climb to 13-under while Watson matched him with a birdie on the same hole to retain the margin.
On the following hole Watson made the first of back-to-back bogeys while Irwin began his charge on the fifth with a birdie and took the lead outright at minus-14.
Irwin then birdied the sixth and ran home a long birdie putt on the seventh to take a two-shot lead over Watson at 16-under. But the 56-year-old kept Watson in the game, finding bunkers twice on the ninth for a double-bogey.
The duo was knotted in first place when Dana Quigley joined them in the lead on the 11th with a 12-foot birdie putt.
Watson set up a long eagle putt after reaching the green in two on the par-5 13th. He two-putted for birdie to move to 15-under while Irwin blasted out of a bunker to within six feet for a birdie of his own.
Irwin had a chance to re-take the lead but missed a 10-foot birdie putt on the 14th. Watson capitalized, making birdie with a putt from just off the green.
On the 16th, the same hole Watson aced in the opening round, Irwin hit his tee shot to within 12 feet for a birdie and a share of the lead. It then came down to No. 17, where Irwin walked off with the title.
Jim Dent (66) used an eagle on the 13th to finish tied for third at 14-under 202 alongside Jim Thorpe (68). A trio of players finished one shot further back at 13-under, including Quigley (70). He was joined by Sammy Rachels (67) and Allen Doyle (69).
Ben Crenshaw, who made his Senior Tour debut, came back from an
opening-round 4-over 76 to finish at 1-under 215.
Full-field scores from the ACE Group Classic