Once a playing partner of Jordan Spieth while at college in the United States, Frittelli lost in a play-off in the China Open.
Frittelli, 27, carded six birdies and one bogey to finish 12 under par, one stroke clear of England's David Horsey, Finland's Mikko Korhonen and his fellow South African Jbe Kruger.
Once a playing partner of Jordan Spieth while at college in the United States, Frittelli lost in a play-off in the China Open in April and now has a Tour victory to his name.
He almost found himself in another play-off this time, but Kruger's own fine round was tarnished by a bogey at the last, a 67 seeing him fall one shot shy.
"I'm really happy with the way the week went -- super stoked to get my first win on the European Tour -- I think it's been a long time coming and I am glad to be inside the winner's circle," Frittelli told Europeantour.com.
Sitting 17th in the Race to Dubai, the win boosts his chances of qualifying for next month's British Open at Royal Birkdale.
"Hopefully I get into The Open with this performance and it should move me up the Race to Dubai and open up some more doors down the road," he added.
He had started the day on seven-under, two shots behind overnight leader Felipe Aguilar.
The Chilean had led after each of the opening three rounds but fell away after carding five bogeys in a three-over-par round of 75.
He finished tied for 10th on six under par, while Frittelli birdied three of the first four holes and recovered from a wobble at the start of the back nine to see out the victory.
A birdie at 16 and then two pars to finish allowed him to hold off Kruger.
Horsey, who matched the course record with an eight-under 64 on Friday, produced a flawless final round of 65, featuring seven birdies, but fell just short.