Starting his round with a five-stroke cushion, the 26-year-old signed off with a bogey-free four-under-par 68, playing his last 59 holes at the Blackstone Golf Club win Seoul without dropping a shot to finish on 18-under for the tournament.
Richie Ramsay, who closed with a 65, did manage to reduce the gap to three shots at one stage but never really posed a serious threat to the runaway winner, who had previously finished second twice last season.
"I just tried to enjoy it and I had the three best rounds of my life," Wiesberger told reporters.
"I tried not to make bogeys and I did that pretty well, it was awesome. My game plan was to hit as many greens as possible and try to make putts, and they dropped in the end.
"I didn't get nervous, I had three or four shots. There was a pretty shaky moment at 12 but I made a great chip and a putt for par, but I just tried to enjoy it the last three or four holes in," the Austrian added.
Ramsay sunk his sixth birdie of the day at the 16th to close the gap to three but the leader was unperturbed.
Wiesberger came up with a glorious pitch at the 15th to eight feet, holed a 20 footer at the next and sunk a 15-foot birdie putt at the last to seal the title.
"I played with him a few times on The Challenge Tour and he's a top-class guy," Ramsay said.
"If you're going to get beat by somebody, it might as well be Bernd because he's a good guy," the Scot added.
Australian Marcus Fraser finished tied third at 11-under, one shot ahead of Ryder Cup veteran Miguel Angel Jimenez.