Casey, who now resides in Scottsdale, Ariz., accumulated a total of 39 points for three rounds to sweep ahead of the Australians who had dominated the leaderboard over the first two days. Stuart Appleby was second with 33 points and Sweden's Robert Karlsson third with 31.
"Paul was just lapping me, running around me, dancing around me," Appleby said. "He made it look easy today, but it was hard work even though he looked so good at times.
"He's a good player. He hits it long, strong, good touch, good chipping, good putting. The guy's going to play well for a long time."
Casey bogeyed the first hole, but reached the turn in 30 with six birdies and an eagle. He birdied four more holes on the back nine.
"I think the format encourages you to forget what score you are on," Casey said. "You are out there to make birdies and try and make eagles. I've always thrown a lot of birdies and eagles in my rounds, but unfortunately a lot of bogeys too. I think this format suits me. It rewards the aggressive."
Another Englishman, England's Nick Dougherty, shared fourth place with Australian Nick O'Hern after completing a remarkable turnaround. Dougherty barely made the cut riday and then earned 17 points Saturday.