Two men aged 18 and two males aged 15 and 17 were arrested on suspicion of murder on the morning of Thursday, 25 March following warrants in east London.
They remain in custody at an east London police station.
Bubacar Jabbie Dukureh, 17, who was known to his family as Bubacar Jabbie, was attacked in Walthamstow on 23 October 2020.
Officers were called at 21:20hrs to Westbury Road, E17, after Bubacar Jabbie was found suffering from a stab injury. He was treated by paramedics, however despite their best efforts, was pronounced dead at the scene.
A post-mortem examination held on 27 October 2020 established the cause of death as a stab wound to the chest.
Detective Inspector Joanna Yorke, from the Met’s Specialist Crime Command, said: “This was a senseless and violent attack on a teenager on the streets of London.
“Our team has been working hard to establish the full circumstances around the incident and this is a significant update in the investigation.”