Oscar Sharpe sunk a putt on the third play-off hole to win the first Future Collegians World Tour event of the season.
The Cheltenham golfer, who turned 15 last week, was competing in his first tournament since he moved to the United States last month.
Sharpe is working on his bid to become a future world number one in the warm Floridian climate at David Leadbetter's IMG Academy in Bradenton, and his first US win was in the Boys 16-18 Division of the TPC Tampa Bay Open.
Connor Arendell, who graduates in 2008, took the first round lead by firing a one-under par 70.
Arendell, an FCWT All-American, carded four birdies on the day for a two shot advantage over Derek Baade (2009) and Chun Hung Chan (2009) going into Sunday's final round.
That is when FCWT newcomer Sharpe (2010) and FCWT veteran Stanislav Matus (2008) each fired a final round of two under par 69.
Sharpe and Matus began the day tied with three others for fourth place after opening with rounds of +2, but they were now were heading for a play-off for first place.
The final holes of the tournament had just finished when the rain came, but the play-off had yet to begin. After waiting for more than an hour, the duo finally headed back to the course and made birdies on the first play-off hole.
They tied again on the second hole, but on the third Matus found the water. Sharpe's putt lipped the cup but the ball dropped as he earned his first FCWT title in his first FCWT event.
Overnight leader Arendell finished third after a final round of +2.
Sharpe is not a household name in the United States yet, but after winning all four age-group titles from Under-13 to Under-16 in England last year he has already been tipped as a major winner of the future.
He led the division in birdies, with nine for the event, while Matus led in pars with 30.
Sharpe's father Michael was travelling back from the US as the teenager teed off, learning of the victory through a call from Florida.
He said: "Oscar called to say he'd shot a two-under on the second day and he thought he'd be right up there.
"Then to go and win it in a play-off incredible. I think he's the first overseas player to go there and win his first event on the tour.
"He's settling in really well - he's been gobsmacked by the facilities over there - but he's focusing on his golf and we're all delighted with this first win."
Sharpe has been rewarded with an invitation to the Daily Telegraph Junior Championship at Dubai Creek Golf and Yacht Club next week.