The Australian entered the closing round trailing front-runner Johan Edfors by three shots, but charged to the top of the leader board by making birdies on the first five holes.
The birdie at the third gave him a share of the lead and birdies at 10 and 11 put him in charge the rest of the way.
"I just came out of the gates firing this afternoon," said Scott, whose 61 was the lowest final round by a winner since Jamie Spence's 60 won the 1992 European Masters. "Today was pretty special."
Henrik Stenson, the 2006 champion, was the runner-up after a closing 7-under 65 left him at 17-under 271.
South African Carl Schwartzel (67) was third and Edfors (70), a three-time winner in the 2006 season, finished fourth at 14-under 274.