The 44-year-old Senior, who had a five-stroke lead after both the second and third rounds, finished with a 17-under 271 total. He three-putted the 18th for a bogey, his second in a row.
'I was leaking a bit of oil at the end, but I hung on,' said Senior, also the Australian PGA winner in 1989. The victory was his first since the 1997 Canon Challenge in Sydney.
Australia's Rod Pampling shot a 69 to finish second, and countryman Craig Parry was another stroke back after a 70.
Americans Chip Beck and Ryan Palmer were the only non-Australians in the top 15. Beck had a 68 and Palmer shot a 75 for 7-under 281 total. Rich Beem, the 2002 PGA champion, shot a 70 for a 3-under 285 total.
Greg Norman, with tennis star Lleyton Hewitt working as his caddie, finished with a 75 for a 6-under total.
'We had a great week,' Norman said. 'I think it was as memorable for Lleyton as it was for me. Irrespective of how I played, he had a great time and I'm glad we could do it.'
Hewitt, a former U.S. Open and Wimbledon singles champion, said working with Norman was 'one of the best experiences of my life.'
The Australian Open is next week at Moonah Links in Melbourne.
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