Eaks, who never finished better than seventh in a PGA TOUR event and was winless in 90 events over six seasons on the Champions Tour, shot a 6-under 66 on Sunday to win the inaugural Dick's Sporting Goods Open.
Eaks, a self-taught golfer from Colorado who has five runner-up finishes the past two years, completed the three rounds over the narrow and tricky En-Joie Golf Club course at 17-under 199. He won $240,000 to push his earnings for the year past $1 million.
Not bad for a guy who was told after his only golf lesson to give up the game.
'I honestly didn't know if I could win a tournament,' Eaks said. 'Man, this is great! I want to do it again.'
Tour rookie Bruce Vaughan, bidding to become the first open qualifier to win a tournament since Pete Oakley won the 2004 Senior British Open, provided the only real challenge. But Vaughan (68) never mounted a charge over the closing holes and finished second, three shots behind.
Lonnie Nielsen had a closing 67 to finish third at 10 under, one shot better than D.A. Weibring (66) and Andy Bean (68).
Scott Hoch (73), seeking his second win of the year, missed four birdie putts on the front nine, never found his touch on the backside and finished tied for sixth with John Harris (69) and Boonchu Ruangkit (69), nine shots behind.
Eaks began the day with a one-shot lead over Vaughan and a two-shot advantage over Hoch. It was just the second time in his Champions Tour career that Eaks had led going into the final round. He led Bob Gilder by one stroke after 36 holes at the 2005 SAS Championship before closing with a 77 and finishing in a tie for 10th.
This time he was aggressive from the start and didn't falter, even with Hoch and Craig Stadler, who counts the 1982 Masters as one of the 13 tournaments he won on the PGA Tour, in close pursuit.
Stadler was three shots behind Eaks to begin the round. He was 2 under on the front side and a birdie at No. 10 moved him to 11 under. But a bogey at No. 14 and a double-bogey at 15 took him out of contention. He finished with a 73, tied for ninth with Jack Ferenz.
Eaks is known for his distance off the tee and he used it to open a three-shot lead at the turn.
After making birdie at the par-4 second hole, he hit his second shot at the 554-yard, par-5 third hole within six feet of the pin and made eagle to get to 14 under.
The thunderstorms that were forecast never materialized, but a stiff, gusting wind briefly buffeted the course while the final threesome was playing the par-5 fifth hole.
And the 55-year-old Eaks, who had five drives ricochet harmlessly off trees on his bogey-free, second-round 62, kept his string of good luck going. His drive struck a spruce tree along the right side of the fairway, the ball bounced back onto the fairway, and he parred the hole.
Eaks saved par at the par-3 seventh hole, which he aced on Saturday, with a brilliant shot out of a greenside bunker that traveled across the expansive green and stopped 3 feet from the pin.
And when Hoch and Vaughan elected to lay up at the par-5 eighth hole, Eaks took a wood from his bag, drilled a shot over the five greenside bunkers onto the green, and two-putted from about 15 feet for birdie to reach 15 under.
Vaughan rallied with a birdie on the next hole, but Eaks replied with one of his own to maintain his three-shot cushion at the turn.
'I'm throwing everything but the kitchen sink at them, but they're hanging right in there,' Eaks said as he headed for No. 10.
Vaughan moved within two shots of the lead with a birdie on the next hole, but when Eaks faltered at the par-5 12th hole Vaughan failed to capitalize.
Eaks' second shot landed under some trees to the right of the green and he had to punch out, the ball landing short of the green. But Vaughan drove into the right rough and hit his third shot just over the green to the edge of a sand trap, and both players ended with pars.
Eaks secured the breakthrough triumph when Vaughan dropped a shot at the par-4 16th hole, two-putting for bogey from just over 7 feet.