Starting the final round with a two shot lead over Tim Hart and Sean Riordan, Nisbet struggled to get going on the opening nine holes.
Nisbet came through the turn at 2-over the card and found himself four shots off the pace.
Fellow Queensland young gun Tim Hart had capitalised on his early opportunities to be 4-under the card and leading the field heading to the back nine.
Nisbet found a momentum shift on the 10th where he made birdie while Hart struggled with a bogey.
Playing steady golf through the middle of the back nine, Hart had a costly three putt, after driving the green, on the par-4 15th while a birdie for Nisbet saw Hart's lead diminish to just one shot.
With the pressure now on Hart he failed to get up and down on the 17th and headed to the final hole tied for the lead with Nisbet on 13-under the card.
When Hart's approach to the par-5 18th hole finished just six feet from the flag, Nisbet responded by draining a 25 foot birdie putt to post a tournament total of 14-under 270.
"It was a left to right putt and knowing Tim was in there close, I just wanted to give it a chance to go in. When it went in though it was a bit surreal – one of the moments you only dream about," said Nisbet.
With the pressure on, Hart holed his putt to join Nisbet at 14-under the card and force a playoff.
Playing holes 10, 11 and 18, the lowest aggregate score would decide the 2015 Morobe Open champion.
The playoff went down to the wire with both players making birdie on the 10th and 11th. The 18th once again becoming the pivotal hole in the tournament.
With a large crowd watching on, Hart missed the green with his third shot but managed to get up and down to save par.
Nisbet nailed his eight foot birdie putt to claim his first pro-am victory on international soil.
"I have been thinking about winning my first four round professional tournament for so long, and it is everything I ever imagined it would be," added Nisbet.
"It's my first time to PNG, I really didn't have any idea what to expect but I was really pleasantly surprised at the course."
"More importantly the great hospitality the people has shown us this week has been second to none."
Both Hart and Nisbet are coached by 2013 QLD PGA Teaching Professional of the Year Richard Woodhouse.
"Richard has been a great support both on and off the course and we have made some good progress over recent months," said Nisbet.
"I have been working on some better hip movement on my down swing and under pressure today it really held up well."
"Finishing 9th at last year's Australian Open was probably the difference out there today. I certainly drew from what was the most pressure I had ever been under at the time and I have no doubt it helped to get across the line today".
Nisbet takes home more than AU$20,000 for his efforts, the lion's share of the AU$110,000 prize money.
This victory has also taken him to the top of both the Choice Hotels PGA Pro Am Series Sunshine Swing Order of Merit and the PGA's National Rankings.
The Professionals now head to the Royal Port Moresby Golf Club for next week's AU$152,250 South Pacific Export Papua New Guinea Open.
Tour Pros Steven Jeffress, Paul Spargo, Josh Younger and Ryan Lynch will join the strong line-up in PNG for what is an opportunity to win a national open.
The Sunshine Swing forms part of the Choice Hotels PGA Pro-Am Series which comprises of 200 events Australia wide and the Asia Pacific region.
Played across more than 170 golf courses the Choice Hotels PGA Pro-Am Series plays an important part in the development of Australia's Professional Golfers whilst also growing the game at a grass roots level by engaging an estimated 48,000 amateur golfers each year.
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