Romero, who finished well ahead of the final pairing of Lonnie Nielsen and Bobby Wadkins, posted the low round of the week with his 7-under 65. That got him into the clubhouse at 13-under-par 275.
Wadkins had a chance to get into the playoff, but he posted just one birdie to go with 17 pars. That left him one stroke out of the playoff at 12-under-par 279.
In the playoff, Nielsen found a fairway bunker off the tee and did not have a good lie. His second shot hit the lip of the bunker and kicked into the trees right of the fairway.
Nielsen had a good look though from there. He hit a fairway wood from nearly 275 yards just short of the 18th green at Reserve Vineyards & Golf Club.
Romero, after watching those two shots, knocked a fairway wood of his own onto the green, 18 feet from the hole.
Nielsen pitched on, but could only two putt for bogey from 16 feet out.
Romero, who had rolled his eagle putt to 2 feet before Nielsen putted, tapped in for birdie and his first tour win. He joins Jack Nicklaus, Tom Kite and Loren Roberts as those who made this event their first Champions Tour win.
'It feels very strange (to finally get this win). I'm very happy though, I played good all week,' Romero said. 'This is my first victory on the Champions Tour and I'm very, very, very happy. I hope there will be more to come. I'm very excited, I don't know what to say.'
Mark James (67), Tom Kite (71), Larry Nelson (70) and Tom Purtzer (70) finished in a tie fourth place at 9-under-par 279.
Romero caught fire early on the front nine. He holed out for eagle on the par-4 fourth, then birdied each of the next two holes to move to 10 under. A birdie on the par-4 eighth moved into a share of the lead with Nielsen and Wadkins.
The Argentine cooled with seven straight pars.
Meanwhile, Nielsen traded a birdie for a bogey from the sixth. Birdies on nine and 12 moved Nielsen to 13 under. However, he gave a stroke back with a bogey on No. 13.
Romero birdied the par-5 16th to move into a tie for the lead again at 12 under. At the par-5 18th, Romero found a greenside bunker with his second. He blasted out to 15 feet and sank that birdie putt to end at minus-13.
'I've been working hard to get a good result for next year,' said Romero of gaining exempt status for 2007, which he earned with the win. 'Today, the key was my putting. It was good today. I hit my driver well and today was my best day thinking.'
Nielsen parred four straight from the 14th. At the last, he got a good bounce over a bunker. He then pitched to two feet and tapped in for birdie to force the extra session.
Wadkins' lone birdie came on the 12th. So he stood at minus-12, but was unable to make another birdie the rest of the way. At the last, his second shot bounced hard off the green and into very thick rough. He pitched onto the fringe and two-putted for par when he needed a birdie.
'I was pretty well hosed. I think we could have put the greatest player in the world there, Tiger Woods, and he would have had a hard time getting up and down,' Wadkins said of his shot from over the 18th green.
'I hit a drive as good as I could hit it and a 3-wood the way you draw it up on the practice tee. Everything about it looked good, but it didn't work out. I didn't do what I had to do today.'
Andy Bean ended in eighth at minus-8, while five players were one stroke further back.
Roberts, the 2005 champion, struggled to a 4-over 76 Sunday and ended in a tie for 14th at 6-under-par 282.