Sterling got to the winner's circle when David Lutterus, who shared the overnight lead with Sterling and Peter Senior, and was tied with Sterling on the 72nd hole, bogeyed the par-4 18th.
That gave Sterling a one-shot victory at 12-under-par 276. Lutterus posted an even-par 72 on Sunday for second place at minus-11, while Marc Leishman (69) and Brendan Jones (71) tied for third place at 10-under-par 278.
'You always have some kind of doubts but to come out on top is great,' said Sterling.
Conditions were difficult early on in the final round and most of the field struggled in the blustery wind.
Sterling and Lutterus were not immune to the early trouble. Both players were 2 over par through four holes as Sterling tallied a pair of bogeys, while Lutterus mixed three bogeys and a birdie.
Both players calmed down and collected pars, but Sterling reached 10 under par thanks to a birdie at the ninth. Lutterus joined Sterling at minus-10 with a birdie at 10, but Sterling fell one behind because of a bogey at the par-4 11th.
Sterling got back to 10 under par with a birdie at the 12th. He recorded birdies at the next two holes to take the lead at 12 under par. Lutterus birdied the 13th and par-5 16th to join Sterling in a tie atop the leaderboard.
Lutterus made a mess of the 72nd hole with the championship on the line. He missed the fairway with his tee shot, then his approach ran through the green. Lutterus could do no better than bogey.
'I had a good feeling about today, I thought I was going to win,' acknowledged Lutterus.
Sterling played the hole routinely and two-putted for par and the win.
This was Sterling's first win on the Nationwide Tour, a circuit he played regularly from 2002-2005. His previous best finish was a tie for fourth at the 2003 Lake Erie Charity Classic.
Last year, Sterling worked on his craft on the Tight Lies Tour and finished first on the money list with over $72,000. For his victory on Sunday in Australia, he pocketed $145,586.
Senior struggled to a 2-over 74 and tied for fifth place with two-time winner on the PGA TOUR, Craig Parry and Brett Rumford, both of whom shot 71s on Sunday. The trio came in at 9-under-par 279.
Nick Flanagan (69), Peter Wilson (72) and Brad Ott (74) shared eighth place at minus-8.