Even by the world number one's standards, this was a remarkable victory as he got the better of Ireland's PadraigHarrington in a compelling last-round head to head.
England's world No. 1 Luke Donald (73) finished the tournament on the same total, as did Ireland's PadraigHarrington (71) -- who will be looking to win a third Open Championship after his back-to-back successes in 2007 and 2008.
The Republic of Ireland's three-time major winner PadraigHarrington told a news conference in Copenhagen that the Olympics would soon surpass the majors in importance.
McDowell, ranked 19th, triumphed 3 and 2 on Saturday as he followed up his wins against Ireland's three-time major champion PadraigHarrington and world No. 51 Alexander Noren of Sweden.
Ireland's PadraigHarrington stayed in touch with the leaders with a four-under 68 while Sweden's Joakim Haeggman fired six birdies to reach the clubhouse in fifth place with a six-under 66.