Lonard, tied for third entering the final round, finished at 9-under 279 - one shot better than Chris Downes, who led through the first three rounds, and Stephen Leaney, who led for most of the final round.
'It's a wonderful way to finish the year. To be part of golf history for all time,' he said.
'You look through the list of winners, it's a catalogue of the best golfers of all time. I'm privileged to be part of it.'
Leaney had the chance to force a playoff with an eight-foot putt on the last hole, but the ball rolled short and to the left, denying him his first victory since the Linde German Masters in 2002.
'I guess I can't be disappointed,' said Leaney, who also finished runner-up in this year's U.S. Open.
'It's just a shame I couldn't make the putt on the last. Pete did what he had to do and he's a worthy champion.'
At one point Sunday, seven players - including 2002 U.S. Amateur champion Ricky Barnes - held a share of the lead. Barnes three-putted the final hole for a round of 73 to tie for ninth at 5 under.
Stuart Appleby finished a shot further back. The 2001 Australian Open champion had a triple bogey-7 on the third hole after hitting a shot out of bounds. He also had five bogyes to just two birdies and one par over his first nine holes. After making the turn in 42, he came home in 32 to tie for 11th at 4 under.
Lonard had two birdies and two bogeys in his opening nine holes, but won it with birdies at Nos. 13, 16 and 18 and a pressure par from the back of the 17th green. He earned $200,000 and won the Australasian PGA Order of Merit crown.
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