Eger, whose best finish was a tie for ninth at the SBC Senior Open last season, also picked up his first win as a professional.
'I hate to use the cliche, but it still hasn't sunk in yet,' said Eger. 'When I started, I only thought I could win if I had a round in the mid-60s.'
The champion started quickly with a five-foot birdie putt at the first. He then two-putted for birdie at the par-5 sixth. Eger, a North Carolina graduate, drained a 20-footer for birdie on the eighth to make the turn at minus-8.
On the back side, Eger dropped a wedge within three feet of the cup at the 10th to set up another birdie. He again two-putted for birdie at a par-5, No. 12, to climb to 10-under.
However, Eger knocked his tee shot on the 13th out-of-bounds. He was able to card a bogey, but did fall to minus-nine. Eger came back with a birdie putt at the 15th from seven feet.
Eger then moved to the top of the leaderboard over the final two holes. He knocked a 9-iron to 18 feet at the 17th and rolled in the birdie putt to get to minus-11. On the 18th, he stuck a pitching wedge within four feet and sank the birdie putt for the outright lead.
'I never thought about winning until I picked up my ball out of the 18th hole,' said Eger, who claimed $300,000 with the win. 'I fully expected a playoff and would have been happy with that. I intend to use this as a confidence builder.'
He then had to watch the final three groups complete their play.
Irwin began his round tied with Eger, but played one group behind him. He made his move quickly on the front nine. He birdied three straight holes from the second. After parring the fifth, Irwin birdied the sixth to help him make the turn at minus-9.
Irwin, who has won 36 times on the Champions Tour, faltered with a bogey at the par-3 11th. He did close with three birdies over the final four holes but fell one shot short.
Jenkins, Darcy and Lietzke each shot 70 in the final round. Jenkins bogeyed the second, but closed with birdies at Nos. 12, 13 and 17 to climb into a share of second place.
Darcy, who was making his Champions Tour debut, birdied the fourth and ninth to get to minus-11. Darcy then dropped a shot with a bogey at the 10th. He came back with a birdie at the 16th, but could only manage pars on the final two holes.
Lietzke, who came back from five shots down in the final round last year, took a big lead early on. He moved to 12-under par with birdies at the Nos. 3, 6 and 8. On the back nine it was a different story.
Around the turn, Lietzke was unable to get up-and-down for par at the 11th and fell back to 11-under. He erased that mistake by two-putting for birdie at the next. He failed to defend his crown as his second shot to the par-4 16th found a hazard and he went on to bogey the hole and drop into second place.
'It was disappointing from just about every aspect of my game,' said Lietzke. 'I am disappointed with my swing on the back nine. I mishit some tee shots and some iron shots.'
Lietzke thought he was tied for first on the final hole and heading for a possible playoff.
'We were playing the 18th thinking we'd be playing for a possible playoff,' Lietzke said. 'I didn't see a leaderboard to see someone at 12-under. Tom Jenkins last saw a scoreboard on 15. We were all in shock when we found out that Eger was at 12-under.'
Walter Hall finished alone in sixth place at 10-under-par 206. Steve Veriato, a Monday qualifier, was two shots behind at minus-8, alone in seventh place.