'I played with Craig Stadler last week and watched how he played and how he did it,' said Levi, who claimed his second Champions Tour title. 'He just kept making birdies.'
Irwin fired a final round 8-under 64 to putt pressure on Levi, but he came up two strokes short. Rodger Davis took third place at 13-under-par 203, with Jim Thorpe and Graham Marsh one stroke further back at minus-12.
Despite not being the longest of hitters, Levi took advantage of both front-nine par-5s. He pitched his third shot to 4 feet to setup up birdie at the second. That was his third birdie in three days on that hole.
Levi came back with a birdie at the fifth, from 12 feet, for his third birdie in three tries on that hole. He did miss short birdie tries on three of the next four holes however.
The 52-year-old Levi ran off five straight pars around the turn, then moved to 15 under when he kicked in a short birdie putt at the par-3 11th.
Once again, Levi took advantage of a par-5. He dropped his third shot to the par-5 16th within 10 feet of the hole and converted the putt. He played that hole at minus-4 for the week with an eagle and two birdies. He then closed with a pair of pars.
'The turning point may have been the 12th where I made a good 6-footer there to save par,' said Levi. 'I knew I needed to be 3- or 4-under to stay ahead of these guys. The birdie at 16 cemented things.'
Irwin, the Champions Tour's all-time wins leader, used a hot back nine to roar from 13th place to second. He birdied the first, but gave that stroke back with a bogey at the third at Hayfields Country Club.
He drained a huge putt from over 90 feet out for eagle at the fifth and came right back to birdie the sixth. Irwin tripped to a bogey at the 10th to slip back to 8 under. He caught fire from there as he closed with six birdies over the final seven holes, including five straight from the 12th, to jump to minus-14.
'I'm really pleased how I played,' said Irwin, who missed last week's tournament with a stiff neck. 'I'm still hitting some wayward shots after not playing last week. I felt like I was playing myself into shape this week.'
D.A. Weibring and Jerry Pate shared sixth place at 11-under-par 205. Jay Overton and Jose Maria Canizares finished one stroke further back at minus-10.
Tom Watson, who is to undergo hip surgery this week, posted a final-round 71 to end at 9-under-par 207. He was joined there by Gil Morgan. Larry Nelson, the 2003 champion, finished well off the pace at 2-under-par 214, where he tied for 45th place.