Romayne Husbands, 28, of Winchester Road, was found guilty by a jury at Snaresbrook Crown Court on Friday following a two-week trial.
It was a re-trial after he had previously been convicted of murder in June 2021.
Husbands also pleaded guilty to possession with intent to supply cocaine. He will be sentenced at the same court on Tuesday, June 6.
Victim Jay John, 27, was outside a communal door of a block of flats in Trinity Close when when Husbands attacked him on April 25, 2020.
Witnesses told the court that Husbands punched Jay in the face then stamped four to six times on his upper body.
Officers rushed to the scene and arrested Husbands in a nearby flat, where he discarded 59 grams of cocaine.
Jay was found unconscious but breathing on the floor in Trinity Close. He was treated by police officers and paramedics at the scene for a wound to the back of his head. He also had facial injuries including a fractured eye socket and cuts and bruising to his face, lips and jaw.
Jay was pronounced dead in hospital the next day. A post-mortem examination gave the cause of death as head injuries.
A murder investigation was launched and detectives linked Husbands to the scene via blood found on his trainers.
Detective Ben Dalloway, of the Met’s Specialist Crime Command, said: “This was an extremely violent assault by Romayne Husbands in which he stamped on Mr John numerous times, leaving him for dead. I would like to express my gratitude to the members of the public who witnessed the harrowing event and had the courage to attend court and give evidence for a second time.
“Romayne Husbands is a convicted drug dealer which I believe accounts for his presence at the scene on that day and, to some extent, his erratic and violent behaviour.
“Finally, I would like to express my condolences to Mr John’s family and friends, our thoughts are with you.”