The Thai only entered this event seven days ago and arrived having not played any practice rounds at Karrinyup Country Club.
He needed four trips up the 18th in a play-off on Saturday night to claim the last of the 24 spots in the Super 6 and then had to come through five rounds of match play and 35 holes on Sunday.
After wins over Ben Eccles, Yusaku Miyazato, Sean Crocker and Lucas Herbert, he produced one final push to beat Australian Nitties and move back into the top 50 in the Official World Golf Ranking.
The victory is the 28 year old’s second in a match play event after his win at the 2015 Saltire Energy Paul Lawrie Match Play.
“It’s just been an awesome week,” he said. “I don’t know how to explain but I’m so happy.
“I’m working so hard. The last few months I’ve been getting really close and finally I’ve done it.
“It means a lot. When you focus on something, you try this hard, then I kept finishing second and then I’m not giving up. I’m trying so hard until I get it.
“It’s really tough to get in the last 24. It’s been tough every single match that I play in.
“James is playing so good but he’s just unlucky at the end.”
I’m working so hard. The last few months I’ve been getting really close and finally I’ve done it – Kiradech Aphibarnrat
After 54 holes of stroke play, the players were facing off against each other over the tenth, 11th, 13th, 14th, 12th and 18th, with the 90-yard shootout hole used to separate those still all square.
Nitties hit an excellent approach into the first while Aphibarnrat found the sand and, when he failed to get up and down, he was one down.
It was advantage Aphibarnrat on the second after Nitties was behind a tree off the tee and put his third into the sand but Aphibarnrat could only make a five and the hole was halved.
There was more tree trouble off the tee for Nitties on the next and this time he could not make par, with a four from Aphibarnrat enough to get him back to all square.
An incredible tee-shot to three feet on the driveable fourth set up an Aphibarnrat eagle but he had to hold his nerve to make the putt after Nitties made a remarkable birdie from the trees.
Both men hit good tee-shots into the fifth but when Nitties missed his putt, Aphibarnrat took his chance from ten feet.
Nitties had defeated Nick Cullen, Dimitrios Papadatos, Callan O’Reilly and Sam Horsfield en route to the final, with Englishman Horsfield finishing fourth after losing 3 and 1 to Herbert in the 3rd/4th play-off.
“It’s a sad way to go down considering another win might have got me some playing rights somewhere in the world because I currently have no status but it was a great week,” said Nitties.
“Considering I was a four-footer away from losing the first match, it was pretty positive stuff getting to the finals.
“It’s just absolutely fantastic. The weather’s perfect, it’s beach views every day most of the time. I couldn’t complain at all. It’s a fun week and I love this tournament.”