The 16-year-old boy, who cannot be named for legal reasons, was arrested after arriving into the UK at Gatwick Airport on Thursday.
He has been charged with murder and grievous bodily harm.
He will appear in custody at Bromley Magistrates’ Court on Saturday.
Police were scrambled to Seward Street on December 20 and found two 16 year-olds wut stab wounds at around 10.30pm.
Officers provided emergency first aid until the arrival of paramedics and doctors from London’s Air Ambulance.
One of the boys, Jamaly Samba Baibu, was pronounced dead at the scene. His family are being supported by specialist officers.
The second boy was taken to an east London hospital where his injuries were assessed as not life threatening.
The investigation is led by homicide detectives from the Met’s Specialist Crime Command.
Another 16-year-old boy, who was arrested on suspicion of murder on Tuesday, 27 December, has since been bailed pending further enquiries to a date in late January.
Anyone with information is urged to call 101, with the reference 7708/20Dec. To remain anonymous contact Crimestoppers on 0800 555 111.