Ryo Hisatsune made a back-nine charge to claim the French Open on Sunday and become only the third Japanese golfer to win on the DP World's European Tour.
The 21-year-old, in his rookie season, was lying four shots off the lead overnight and seemingly out of contention.
But a brilliant back-nine of 30 courtesy of five birdies left him signing for a final day 66 to finish 14 under par at Le Golf National.
"I'm flying back to Japan tomorrow. I might upgrade to Business class now," he joked after this landmark win.
He added: "I had confidence today and also a lot of luck.
"I didn't think of the result on the back nine, just concentrating on my golf."
England's Jordan Smith and Dane Jeff Winther tied for second, two shots back.
Another Dane, Rasmus Hojgaard, was at 11 under, one clear of Austrian Lukas Nemecz and two ahead of local favourite Julien Brun, Japan's Kazuki Higa, South Korean Tom Kim and German Yannik Paul.
Hisatsune, who only secured his European Tour card less than 12 months ago, emulates Isao Aoki, Japan's first DP World Tour winner at the 1983 European Open, and Hideki Matsuyama, winner of the 2016 WGC-HSBC Champions who went on to win the 2021 Masters at Augusta.
Le Golf National is the venue for the Olympic golf tournament at the Paris 2024 Games.