Harries, who was runner-up in the British under-20s to Romell Glave, won the 200m by a metre in 20.81, improving his legal personal best from 20.89 in the semi-final.
His best time of 20.56 was a windy performance from finishing second in the 2015 Commonwealth Youth Games.
Jona Efoloko completed a sensational British one-two, finishing second just a tenth of a second back in 20.92.
Harries said: “Last year I was on crutches and in a leg brace after having surgery. I’ve battled through all the rehab and there were times when I didn’t think I’d be back, but I kept pushing and this means the world.”
Harries has just finished his A-levels at Brighton College and starts a new chapter, going to university in September.
The former Chichester Runners junior and Westbourne House School pupil lives in the Angmering area.
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