Wiesberger, who held the overnight lead, extended his advantage to five with his three-day total of 14-under-par 202 at the co-sanctioned Asian Tour and European Tour event.
2010 Ballantine's Championship winner Marcus Fraser of Australia posted a 69 to finish in second place on 207 while England's Oliver Fisher and Chile's Felipe Aguilar are tied for third on matching 208, with Ryder Cup legends Miguel Angel Jimenez and Paul McGinley a further shot back.
Kiradech Aphibarnrat turned the spotlight to Thailand when he charged back into contention with a 65 to become the highest placed Asian in tied-seventh alongside Scotland's Richie Ramsay, England's David Howell and Sweden's Alexander Noren.
Wiesberger, who is seeking his maiden Tour victory this week, showed composure as he shrugged off the pressure from his closest rivals to post his flawless 65 at the Blackstone Golf Club.
"I think that's what we call a great day at the office," said Wiesberger, twice runner-up on the European Tour last year.
"It was fun out there. It was nice conditions again like yesterday, and a really nice set-up for the course. I enjoyed myself out there, made a lot of putts and that was the key to another perfect day.
"I can be quite hard on myself. But I'm trying to calm myself down and today I just had a lot of fun. I felt like I don't have to get too angry with the shots that did not work out perfectly."
The 26-year-old Austrian has never gone into the final round holding a five-shot lead and he hopes that he can continue to take complete control in his first trip to Korea.
"I feel like I'm getting into position more often and can do well when I was in those positions. The last two years have prepared me well and I hope it pays off tomorrow," said the Austrian who finished runner-up twice on the European Tour last season.
Fraser bemoaned his putting and is ready to put aside his disappointment for his final charge at his second Ballantine's Championship win.
"My old man always said to me, just cup it on the chin and move on. I definitely got to do that today and hopefully tomorrow. If I keep playing the way I'm playing and with the low score in me, hopefully I can do that tomorrow," said Fraser
The Australian was left to reflect on several wasted birdie chances which could have allowed him to reduce his deficit.
"I played great on the front nine and could have turned in 6 or 7 under. Some days they don't go in and some days they do. Hopefully they decide to go in tomorrow instead of hitting the hole and bouncing out," said Fraser.
Meanwhile Kiradech, who came close to winning his second title at the Asian Tour's season opening event in Myanmar, is looking for another good finish despite nursing a slight wrist injury.
Starting the day in tied-38th place and eight shots off the lead, Kiradech reached the turn in 34 after four birdies and two bogeys.
He started to ignite his title charge in his inward-nine by storming home with five birdies.
"I can usually hit longer than what I've been doing this week. For some shots, I cannot hit for the greens in two, especially on some of the par-fives. However my putting was really good today and I holed every birdie chance that I had," said Kiradech, who had a driving average of 284 yards.
"I've not fully recovered yet but I think I still stand a chance," added the Thai.