The 26 year old Sydney-sider pulled off a dramatic victory on the final green at the Spring Valley Golf Club to beat a fast-finishing Kurt Barnes.
Arnold, for a time ranked as the world’s No.1 amateur, pulled off a brilliant recovery from a deep bunker to salvage par and keep Barnes at bay.
“When I saw it plugged in the face, it wasn’t a really hard shot if I hit it right. I was lucky enough I did and it rolled up pretty close,” Arnold said.
Arnold sunk the putt to finish with a 68 and 12 under par for the tournament.
“It’s great, especially the way I did it as well, I just sort of hung in there all day,” he said.
Arnold had started the day as joint leader with New Zealand’s Michael Hendry but it was the big hitting New South Welshman Barnes who really threatened for the title.
Coming down the home stretch Barnes chipped in for one birdie and then eagled 71st hole to draw within one shot of the lead.
He had a downhill six metre putt on the final hole to force a playoff bit his attempt slid by the cup.
Hendry, who had a six shot lead after 36 holes, faded to finish third.
Barnes headed into the final day three shots back from his playing partners, Arnold and Hendry, but with a birdie on his opening hole followed by birdies on the 5th and 6th and an eagle on the 7th he looked unstoppable.
“I had to get out of the blocks early and I did, through nine holes I thought it was probably mine to lose,” said Barnes.
A double bogey on the 11th followed by two more bogeys on 13 and 14 had all but worked Barnes out of the Victorian Open until an eagle on the 17th had him back in contention.
“I faltered a bit on the back nine, but I come home strong there.
“I thought if I made my eagle on 17 and Scotty missed his, I was still a chance, but that’s golf.”
Barnes finished with a final round score of 5-under 66 to take him to a tournament total of 11-under par, one shot back from the winner.
Sharing equal fourth were a group of four players headed by former Australian Open winner Peter Lonard.
Klatton takes 2012 Women’s Victorian Open
For the first time the Men’s Victorian Open was played simultaneously with the Women’s Victorian Open with Frenchwoman Joanna Klatten claiming the title after a playoff with Korean Haeji Kang.
Finishing at 8-under, Klatten was enjoying a two-shot lead and a celebratory beer on the terrace as the final group that included Kang played the 18th hole.
Kang interrupted the premature party when she holed out from 80 metres to force a playoff. Klatten had to put down the beer to look for her caddie and her set of clubs among the large gallery gathered around the practice putting green.
Klatten looked beaten on the first play-off hole but holed a five-metre putt to keep her chances alive. When Kang three-putted the second playoff hole it was all over.
Rebecca Flood, who postponed her wedding to play in the tournament, led into the final round but faded with a closing 76 to finish third at five under par.