The Englishman is a six-time Qualifying School and two-time Challenge Tour graduate, who claimed his third Challenge Tour crown just last week at Le Vaudreuil Golf Challenge.
He had only kept his card on the European Tour twice since winning the Q-School in 2003 but his long wait for victory is now over after a closing 73 at Green Eagle Golf Courses handed him an 11 under par total and a one-shot victory over local amateur Allen John, Swede Christofer Blomstrand and Italian Renato Paratore.
The 39 year old held a two-shot lead on the front nine and for much of the afternoon was battling it out with playing partner and joint overnight leader Bryson DeChambeau.
Back-to-back bogeys from McEvoy on the 12th and 13th had the American in the lead but DeChambeau dropped five shots in his last four holes to fall back.
A McEvoy birdie on the 15th edged him back in front but John was already in the clubhouse at ten under as the deaf amateur – who rejoined the unpaid ranks in 2016 after turning professional in 2011 – produced one of the stories of the week with a closing 67.
Blomstrand and Paratore both birdied the last for rounds of 68 and 70 respectively to join John and when McEvoy bogeyed the 17th, there was a four-way tie for the lead.
A lay-up on the last left McEvoy 20 feet up the hill for victory and nerves of steel saw him sink the right-to-lefter for a remarkable victory.
“It’s incredible,” he said. “I’ve waited a long time, 17 years as a pro on and off the Tour. I’m absolutely over the moon. A lot of hard work, a lot of bad years, a lot of good years but it’s never quite happened and it was my time on that 18th green today.
“I fought hard, I believed, and even at the last I overpowered my caddie to lay it up to give myself the best opportunity to make birdie and I managed to do it.
“I’ve tried to enjoy my golf as much as possible. Not that I haven’t been but I just needed to that little bit more and it’s just come up proper trumps.
“It started a couple of weeks ago, I played a pro-am at Queenwood and shot 64 – a course record – and beat the likes of Rory, Justin Rose, Adam Scott and a few other boys and that was the start of the confidence kick, really. Last week was obviously another boost to the confidence and I’ve come good again this week.”
Japan’s Hideto Tanihara and Frenchman Romain Wattel finished at nine under, a shot clear of England’s Paul Casey and Austrian Matthias Schwab.
Masters Tournament champion Patrick Reed was then at seven under alongside fellow Augusta winner Charl Schwartzel, Scot David Drysdale and England’s Matthew Nixon, one ahead of a group containing DeChambeau.
McEvoy started with five pars and while he dropped a shot after finding water on the sixth, a stunning approach to the seventh kept him two ahead. He then found sand on the eighth to drop into a share of the lead with DeChambeau at the turn after a two-shot swing and the field were closing in.
A 15-foot right-to lefter on the 11th edged him back ahead at 12 under but after missing the green on the 12th and 13th, he found himself trailing his playing partner.
An excellent 20-foot effort on the 15th had him back ahead as DeChambeau fell back but McEvoy left himself a devilishly tough chip on the 17th to fall back into a share before his big finish.
John turned in 33 and added another birdie on the 11th before surging through the field with a big finish of his own, taking advantage of the 15th and 16th and hitting a stunning tee-shot into the penultimate hole.
Paratore birdied the seventh and 11th but missed opportunities on the back nine, and a bogey on the 14th looked to have ended his chances before he produced an incredible second from the right on the last to set up a birdie.
Blomstrand turned in 31 with birdies on the second, fourth, and seventh, and made further gains on the 11th and last to go with a bogey on the tenth.
Tanihara signed for a 69, while Wattel missed a short putt for eagle on the last in a 71 and DeChambeau’s dramatic afternoon ended with a score of 78.