The win was Roberts' third straight to open the Champions Tour season. He became the first player in tour history to win each of the first three official events of the year.
'I tell you, this is great. Today was definitely ugly,' said Roberts, who picked up $240,000 for the win. 'The back nine was ugly, but I'm just happy to come through with the victory. It was a tough day.'
R.W. Eaks fired a 5-under 67, but came up one stroke shy as he finished at minus-13. He was joined there by Brad Bryant, who closed with a 70.
Hale Irwin, the all-time wins leader on the Champions Tour, double-bogeyed the closing hole to finish two back. He posted a 68 to join Tom Watson at 12-under-par 204. Fuzzy Zoeller, Tom Jenkins, Rick Karbowski, Gary Koch and Don Pooley shared sixth place at minus-11.
Roberts, who shared the lead with Bryant and Pooley entering the final round, birdied the first at The Club at TwinEagles to remain tied for the lead with Bryant.
The 50-year-old Roberts dropped in a 12-foot birdie putt on the third, while Bryant bogeyed the same hole giving Roberts a two-stroke lead. Roberts drained a long birdie effort on the sixth to regain a two-stroke margin, this one over Pooley.
Irwin, like Roberts, birdied the first and sixth. The 60-year-old birdied eight, 10 and 11 to get within one of Roberts. Irwin tripped to a bogey on the 12th, but bounced back to birdie 13 and 15 to forge a tie for the lead at minus-14.
Roberts, meanwhile, two-putted for par on six straight holes from the ninth. He got up and down for par on 15. After a par on 16, Roberts' drive on the 17th stopped near the lip of a bunker.
He was forced to pitch out. Roberts 4-iron, third shot was a thing of beauty stopping 11 feet from the cup. However, he two-putted for par there to remain tied with Irwin.
'I was kind of fighting my driver today and I snapped it in that bunker there,' Roberts said of the 17th hole. 'I hit it out of the bunker, then I knew that was the suck it up shot. I knew I needed a good shot or it might have been over. I hit a really good approach shot. That was the shot of the tournament for me.'
Irwin also two-putted for par on 16 and 17 to keep his share of the lead. His tee shot at the last found the right side of the fairway. The ball was slightly above his feet which caused Irwin to hit the shot heavy. The ball came up short in the water and after knocking his fourth on the green, he could only two-putt for double-bogey.
'It was a pretty comfortable distance, but the lie was pretty tight and the ball was above me a little bit,' said Irwin of his shot at 18. 'I needed to hit it solidly and I just hit it a little bit heavy and that did it. I knew it didn't have enough once it got in the air.'
Roberts found nearly the same spot in the fairway as Irwin off the tee. Knowing what Irwin did, and that Eaks was finish at 13 under, Roberts calmly knocked his approach to 37 feet. He two-putted for par and the historical win.
Bryant parred eight in a row after his early bogey. He birdied 13 and 18 to climb into a tie for second.
Eaks started the day three back, but birdied three of the first six holes to move to 11 under. He faltered to a bogey on eight, but birdied his next two holes to get to minus-12.
The first-round leader double-bogeyed the 12th, but again recovered quickly. Eaks birdied 13 and 14 to get back to 12 under. He got within one with a birdie on the par-5 17th, but ended there as he could only par the last.
Mark McNulty fired his second straight 67 to end at 10-under-par 206. He shared 11th place with Tom Kite (68) and Peter Jacobsen (69). Keith Fergus, Larry Nelson and Dana Quigley were one stroke further back at minus-9.