Imri Doue, 18, was convicted of murdering Daejaun Campbell whilst Marko Balaz, 19, was found guilty of manslaughter.
Doue, from Woolwich, had not been named or pictured until now as he was under the age of 18.
Daejaun cried out “I’m 15, don’t let me die” after he was ambushed on September 22 last year.
His friend and aspiring rapper Kelyan Bokassa, 14, nicknamed Grippa, had featured in a YouTube music video entitled Gotta Eat, in which he was seen crouching beside a floral tribute to Daejaun.
Then on January 7, Kelyan too was fatally stabbed by two 16-year-old boys with machetes on a bus in Woolwich.
In a televised sentencing on Monday, Judge Sarah Munro KC detained Doue for life with a minimum term of 21 years and handed Balaz, from Abbey Wood, 11 years in custody.
Earlier, Daejaun’s mother Joelle Taylor faced her son’s killers in court and said: “I keep asking when will this knife crime epidemic end?
“The reality is actions like yours tear families and communities apart.”
She condemned her son’s killers as “pathetic cowards” and said Daejaun was let down repeatedly by the system that was “meant to protect him”.
Daejaun was a “true character” who was playful and cheeky and planning a “new start” just before he was killed, she said.
Addressing the dock, Mrs Taylor said: “Your actions have inflicted immense pain on me and my family and I struggle to write something that is not overwhelmed by raw emotion and anger that I feel.”
Mrs Taylor criticised the killers for their “lack of remorse” and said their sentence should reflect the “devastation” they had caused.
