Mully Tambwe, of Romford, has been found not guilty of the murder of 18-year-old Isschan Nicholls.
A jury at the Old Bailey cleared the 23-year-old of the crime, which took place in Bow in January 2010.
His co-defendant Simeon Hunter, 25, of Ambrose Walk, Bow, was found guilty of manslaughter following a five-week trial.
Isschan Nicholls died of stab wounds to the abdomen and thigh after a large fight in Parnell Road.
Hunter was linked to the victim by traces of blood found on his trousers.
He will be sentenced on June 4.
Proceedings against a third man, Joel Ofori, 23, of Bow were discontinued at an earlier date.
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