Wayne Grady carded an even-par 71 to join Brendan Jones and Anthony Painter in a tie for second at 4-under-par 280.
Walters carried a one-shot lead into the final round at Kooyonga Golf Club and picked up back-to-back birdies from the second to move to 8 under.
The Australian gave those shots back with consecutive bogeys starting at the seventh but he managed to respond with a birdie at the par-5 ninth.
Walters kept plugging along on the inward half with a birdie at the 13th to pad his advantage as his challengers struggled down the stretch.
Walters then birdied the par-4 17th to secure a monumental victory for his career in dominating fashion.
'I know I'm richer than I was this morning,' said Walters. 'That's about the extent of it at the moment. Obviously with the exemption that goes with it and all those sorts of things I haven't really thought about.'
Walters, who will play next week at the New Zealand PGA Championship, has plenty to consider with his new status on the Nationwide Tour.
'It's going to be a family decision more than anything,' he said of playing in the U.S. 'Whether it's appropriate to take three children over there. Whether I go for two weeks, come back for three or something like that.'
Jones jumped out of the gate with birdies on each of his first two holes to reach 6 under before finding trouble with a bogey at the par-3 third.
The Australian picked up another birdie at the fifth but stumbled again with a bogey at the very next hole.
Jones fell well off the pace on the back side with a bogey at the 10th and back-to-back bogeys from the 13th. He countered with two straight birdies starting at the 15th for his share of second.
Nick O'Hern posted a 1-under 70 to share fifth place with Scott Gutschewski and Mathew Goggin at 3-under-par 281.
Jimmy Walker, who won the season-opening BellSouth Panama Championship two weeks ago, finished one shot further back at 2-under-par 282 along with Craig Parry, Stephen Collins, Craig Jones, Michael Long, Scott Gardiner and Martin Doyle.
Adam Groom and Mike Sposa finished knotted at 1-under-par 283.