Kevin Kelenda, 18, of Doggett Road, was found guilty of murdering Tyrone Pinnock following a trial at Woolwich Crown Court.
Tyrone died in Kensington on the evening of October 19, 2023.
A member of the public found him suffering from stab injuries in Kensal Road and flagged down a police car shortly before 6.45pm.
Kelenda was 16 when the murder took place.
He turned 18 earlier last month, allowing him to be named publicly for the first time.
He now faces a life prison sentence.
The minimum term of his life sentence will be decided at a sentencing hearing in May.
