The 27-year-old hit a final round five-under-par 67 for a 15-under par total in the Asian Tour event held at the Royale Jakarta Golf Club.
Open champion Els carded a 68 to finish second, while overnight leader Daisuke Kataoka of Japan slipped back to third, a shot further back after a final-round 70.
“I was struggling in the beginning after my birdie on one. But, at the turn, I got a bit of momentum going because I was confident with my ball striking,” said Wiesberger, who took the lead from Kataoka with an eagle-3 on the 12th only to see playing partner Els match the feat.
Els, whose lone bogey of the round came on the fifth hole, was not too dissatisfied with his week’s work. “I played and fought hard. I wasn’t quite at my best but had a good time. I didn’t hit my iron shots close enough, especially at the start. I was one over through five holes and had to battle back all the time,” Els said.
“A win would have been unbelievable but second is not all that bad. I’m starting to feel really good about my game.”