The 52-year-old American, who trailed overnight leader Bernhard Langer by one stroke heading into the final round, closed with back-to-back birdies to secure the win.
Couples’ compatriot Gary Hallberg, the 36-hole leader, finished two shots back in second after carding 66 on a windy and testing Ailsa Course.
“It was a very fun day,” said Couples on www.europeantour.com.
“Being paired with Bernhard, you’ve got to play great and for a long time there, we were neck and neck.
“But for me I felt like I was hitting the ball very strong, very solid, and I was really lucky that it didn’t rain because I’m not very good in the rain!
“That was a big birdie on 17 to make 18 play easier and then when I hit the last putt, the hole got in the way and I won by two.
“I’m very happy and excited to have won this.”
English duo Barry Lane and Carl Mason ended the tournament tied for third place alongside American Dick Mast, with the trio finishing on four under par.
Langer, however, could only card a round of 75 today and had to settle for a share of sixth place.
* Colm Moriarty suffered a disappointing finish to the English Challenge after a 10-over par final round of 82 meant he fell to tied 50th place on one over par at Stoke by Nayland Hotel, near Colchester.
Moriarty began the day in eighth place and made some progress early on after a birdie at the second hole moved him to 10-under par for the tournament but it all went downhill from there and a double bogey six at the fourth hole was followed by a bogey at the par three seventh.
The bad news didn’t end there for the Athlone man and he suffered back to back triple bogey sevens at the ninth and tenth holes before dropping another shot at the 11th.
He did get a shot back with a birdie at the 14th but two more bogeys meant he couldn’t improve on his best finish of 2012, tied 19th.
Stephen Grant also finished the day in tied 50th place after a three over par final round of 75.
Chris Paisley, meanwhile, claimed his maiden Challenge Tour title as a one under par final round of 71 left him two shots clear of compatriot Francis McGuirk on 16 under par.
* Lurgan’s Niamh McSherry left her best until last to produce an inspired one over par 73 on the final day of the European Young Masters at Hungary’s Royal Balatan Club.
It was far too late to challenge for a medal but she did move up 10 places to 37th in the overall ranking and helped Ireland climb one spot to 13th out of the 26 competing nations.
McSherry finished 30 strokes adrift of individual winner Spaniard Covadonga Sanjvan.
Olivia Mehaffey, Royal County Down, posted a closing 76, her performance being spoiled by double bogeys at five and 13.
County Sligo’s David Brady ended with a 77 while Marc Boucher from Carton House, who had been playing well, slumped to an 84 on Saturday.
Both boys were well behind the winner Renato Paratore of Italy who recorded a 209. Italy took the Gold Medal with Spain capturing the Silver and the Czech Republic the Bronze.
* Inbee Park made birdies on her last three holes to coast to victory in the Evian Masters.
The Korean fired a 66 in the final round to finish on 17 under par, two strokes ahead of 2006 winner Karrie Webb, of Australia, and Stacy Lewis from the United States.
Park, the 2008 US Women’s Open champion, took a one-shot lead on to the final hole where she rolled in a 20-foot birdie to secure victory.
Lewis, who shared the overnight lead with Park, made a run at the end but her long putt for eagle on the 18th came too late.
China’s Shanshan Feng also made a late charge with an eagle on the last. She finished joint fourth on 14 under par with South Korean amateur Hyo Joo Kim and American Natalie Gulbis.