Ogilvy had a 19-under 269 total at The Lakes. The 2006 U.S. Open champion won the 2008 Australian PGA for his only other professional victory Down Under.
"I played really well every day," said Ogilvy, who opened with rounds of 68, 65 and 67. "Today was probably the day I struggled most with my game. But all I had to do was not mess up, really."
He slumped after winning the PGA Tour's season-opening event at Kapalua.
"I won the first week and then played relatively horrible golf all year," Ogilvy said. "I didn't enjoy golf as much this year because of how I was playing. But anytime you win an Australian Open you'll look back and think you've had a great year. This is the 90-year-old trophy. This is the real jewel."
Alistair Presnell (67) and Matt Jones (68) tied for second, Jordan Sherratt (67) and John Senden (69) followed at 12 under, and American David Oh (69) was in a group at 11 under. Sherratt was making his pro debut.
Greg Norman (72) and 2009 winner Adam Scott (71) finished 16 strokes behind Ogilvy.