The event, second in the British Triathlon Youth and Junior Super Series, was held before the Vitality World Triathlon in London.
Ivybridge Community College pupil Bramley claimed victory by three seconds in the 500m swim and 2.5km run competition.
He did trail by 15 seconds after the swim but he showed his running prowess on Serpentine Road to make up the gap and finish in time of 13.21 minutes.
Bramley, a member of the Plymouth Tri Club, City of Plymouth Athletics Club and Caradon Swimming Club, edged out Frederick Webb for the title.
After his success in Hyde Park, Bramley said: “Words can’t describe getting on the podium. It has always been my dream.
“Last year I came fifth in the same event, so I never thought I would be top this season.”
The Ivybridge pupil added: “It was a fantastic race – right from the start it was really exciting.
“It was amazing to race on the same course as the Olympic gold medal winners of London 2012.”
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