The Italian finished three strokes clear of England's Jordan Smith with a round of 66 on Sunday to claim his first top-tier title since winning the 2013 BMW PGA Championship at Wentworth.
Manasero made seven birdies in the final round, including one on each of the last four holes, to take home the trophy.
Alongside Smith was South African pair Sean Norris and Thriston Lawrence, the latter's 63 points putting pressure on Manassero, but the Italian won to claim his fifth DP World Tour title. .
“Today was the best day of my life,” said Manassero, who regained his top table spot with two Challenge Tour wins last season but lost his tour card in 2018.
“It's been a crazy journey the last few years. I knew I was on the right track, but you never know what's going to happen.
“Even if I finish No. 18 with a good score, I still have to work hard. Golf is a really difficult game, but I'm really happy to be here with this trophy right now.”
“I think I played really good golf today. The guys behind me were also playing really good golf, and every time I looked at the leaderboard the birdie's name was different, so there was always someone chasing me.
“It was difficult. There were some tough times. Numbers 12 and 13 were a little tough, but I managed to get through it. The finish was great.”
Australia's Jason Skreiner finished tied for 17th with a final round of 68 for a total of 16 under.
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