VERSAILLES, 5 Jul 2015 (AFP) - The 29-year-old Austrian started the last 18 at Le Golf National alone in third, three shots adrift of leader Jaco van Zyl.
A quiet start by him was followed by an hour's suspension of play due to thunderstorm activity and when Wiesberger resumed, sparks began to fly.
Five birdies in six holes from the fourth propelled him into a four-hole lead over the field going around the turn and he never looked like being caught after that.
He punched the air in triumph when a 15-foot birdie putt went in at the last to give him a 13-under total of 271, three strokes clear of England's James Morrison, who took second after a 67.
It was the third European Tour title of his career, the two others both coming in 2012, and it sets him up nicely for a crack at the British Open in St Andrews in two weeks time.
Two shots further back in third came South African van Zyl, who had taken a two-stroke lead into the final round but could only manage a 73.
Former world number one Martin Kaymer of Germany placed fourth after a 70 left him six shots adrift of Wiesberger, with Spain's Rafa Cabrera-Bello in fifth two further shots back.
Wiesberger's win came as no huge surprise to many on the circuit as he has been one of the most consistent performers on the European Tour over the last year and had four top-five finishes this season to his name.
He played in the Masters earlier this year and tied for 22nd, but failed to make the cut at last month's US Open.
"Well, I just hit a great shot down the fourth before the (thunderstorm suspension) horns were blowing and they took us off the course," he said.
"I liked my yardage and had a good shot in there and had some momentum building, chipped in, held a long putt.
"I felt really comfortable out there. Had a great weekend, only one bogey, 66, 65, that's not a bad score."
Morrison, who won the Spanish Open earlier this year, said that all credit was due to Wiesberger for not allowing any of the chasing pack to really challenge him down the closing stretch.
"Bernd played too perfect today. He won the golf tournament today, simple as that. He played fantastic," he said.
Kaymer, the 2009 French Open champion, got to within three shots of Wiesberger going down the back nine, but he left himself with too much to do over the tough four-hole closing stretch and ended with a double-bogey six.
"My plan was really not to play (the tournament) at the beginning because I thought I needed to practise a little bit more to get ready for The Open, but that was the best preparation I could have had, especially playing in the last few groups today," the two-time major winner said.
It was a disappointing day for Victor Dubuisson, seeking to become the first home winner of the French Open since Thomas Levet in 2011.
Starting the day level with Kaymer at four shots off the pace, he had stressed the need for a strong start, but got just the opposite by dropping a shot at the first and then taking a triple-bogey seven at the seventh which ended his hopes.
He eventually had a 75 to place in a tie for 12th.
Leading final round scores in the French Open at the par-71 Golf National on Sunday:
271 - Bernd Wiesberger (AUT) 68-72-66-65
274 - James Morrison (ENG) 71-68-68-67
276 - Jaco Van Zyl (RSA) 68-71-64-73
277 - Martin Kaymer (GER) 69-69-69-70
279 - Rafael Cabrera Bello (ESP) 68-70-72-69
280 - Brendan Steele (USA) 72-69-67-72, Francesco Molinari (ITA) 70-69-70-71, Andy Sullivan (ENG) 71-70-69-70, Michael Lorenzo-Vera (FRA) 75-70-67-68
281 - Maximilian Kieffer (GER) 70-70-65-76, Thongchai Jaidee (THA) 70-74-65-72
282 - Victor Dubuisson (FRA) 68-70-69-75, Tyrrell Hatton (ENG) 71-68-69-74, Kristoffer Broberg (SWE) 72-69-68-73
283 - Richard Bland (ENG) 76-70-66-71, Soren Kjeldsen (DEN) 71-73-69-70, Jorge Campillo (ESP) 70-73-71-69, Jake Roos (RSA) 73-71-66-73, Marcus Fraser (AUS) 73-69-70-71
284 - Daniel Brooks (ENG) 73-66-70-75, Byeong-Hun An (KOR) 71-73-69-71, Jamie Donaldson (WAL) 71-74-69-70, Fabrizio Zanotti (PAR) 73-70-73-68
285 - Marcel Siem (GER) 69-73-74-69, Gregory Bourdy (FRA) 69-72-74-70, Raphael Jacquelin (FRA) 73-71-73-68
286 - Jerome Lando-Casanova (FRA) 74-70-68-74, Mark Foster (ENG) 70-71-68-77, Julien Quesne (FRA) 73-73-73-67
287 - Peter Hanson (SWE) 72-71-68-76, Andrew Johnston (ENG) 73-71-68-75, Anirban Lahiri (IND) 69-77-70-71