Roberts, who won the MasterCard Championship at Hualalai last week, became the third player to open the season with back-to-back wins on the Champions Tour. Don January, in 1981, and Larry Nelson (2001) were the other two players that opened the season with consecutive wins.
Tom Watson, the reigning Senior British Open champion, fired a 4-under 68 Sunday to end at minus-8. He shared fourth place with Don Pooley (71). Allen Doyle was one stroke further back at 7-under-par 209.
Roberts opened the day with a four-stroke cushion on the field. He parred four straight holes before trouble caught up with him. The 50-year-old stumbled to back-to-back bogeys from the fifth.
'It was a struggle today. I missed a short birdie putt on the first hole, then lost a little confidence with the putter,' said Roberts, who collected $250,000 for the win. 'I had a couple of three putts on the front nine and just let everybody in the field.'
Those bogeys dropped Roberts to minus-10 and he was just one stroke clear of Aoki. Aoki got off to a quick start with birdies on one and three. He drained a 15-footer for birdie at the ninth to join Roberts at 10 under.
From out of nowhere, Bruce Summerhays jumped into the fray as well. Playing alongside Aoki, one group ahead of Roberts, Summerhays birdied three straight holes from the seventh to get to 10 under and a share of the lead.
Summerhays had a 12-foot putt for birdie and the lead at the 10th. He missed that, then played the next five holes in plus-5 to tumble off the top of the leaderboard.
Roberts, meanwhile, was scrambling. He had to get up and down for par on three of four holes from the 10th to remain at 10 under. Aoki dropped one shot back with a bogey on the 10th, and fell further back as he bogeyed the par-3 15th.
After a bogey on the first and a birdie on the No. 4, Simpson parred nine straight holes as he lurked two back at minus-8. He moved within one of Roberts' lead with a birdie on the par-4 14th. Simpson then drained a 14- foot birdie putt on 17 to join Roberts in the lead.
Roberts, known as the 'Boss of the Moss' for his putting ability, scrambled to three more pars, as he parred 11 consecutive holes after a bogey on the sixth.
So it all came down to the par-5 closing hole. Aoki birdied 18 to end at minus-9. Simpson and Roberts both found the intermediate rough off the tee. Roberts played his approach first and his 4-iron shot came to rest 9 feet from the cup.
With the pressure on, Simpson could do no better then leave himself 52 feet for eagle. Simpson's eagle effort came up short and right of the cup. Roberts calmly ran his eagle putt into the cup for his third Champions Tour title.
'I said to myself, 'I have an opportunity to really do something spectacular'. I got down to my tee shot and I had an absolute perfect yardage for a nice, cut 4-iron,' said Roberts. 'It was the first perfect yardage I had all day. And it worked out perfect.'
Simpson missed his birdie putt, but the second-place finish was his best finish anywhere since a tie for second at the 2001 Chrysler Classic of Greensboro on the PGA Tour.
Wayne Levi and Keith Fergus each shot 3-under 69s to tie for seventh at 6-under-par 210. They were joined there by two-time Masters champion Ben Crenshaw and reigning Champions Tour Rookie of the Year, Jay Haas.
Summerhays ended in a tie for 11th at minus-five as he closed with a 74. He was joined there by R.W. Eaks and Danny Edwards.