The suspect was arrested by officers earlier today and taken to a south London police station, where he remains in custody.
James Bascoe-Smith, 17, was brutally attacked as he tested out his new bike on Henry Road, Brixton, at 6pm on February 23.
He was set upon by a gang and stabbed multiple times in the chest and thigh and lay bleeding in front of his family as they desperately battled to save his life.
Metropolitan Police Commissioner Dame Cressida Dick said five weapons, including two Rambo-style knives, two ‘zombie’ knives and a kitchen knife, were found at the scene.
James is still in hospital and police say he is making a “slow recovery” after suffering “life-changing injuries”.
His family have been informed of the arrest.
DS Charlotte Carter, leading the investigation, said: “I am continuing to appeal for any witnesses to come forward and speak with my team.
“We are particularly keen for anyone with phone or dashcam footage to come forward. Any piece of information could prove to be vital.”
The Metropolitan Police has previously appealed for information about two vehicles, a black VW Passat and a black Range Rover Evoque, which travelled in convoy from the Kennington Oval area to Henry Road.
The same vehicles then left in convoy with the Passat abandoned in nearby Foxley Road minutes after the attack.
Speaking shortly after the assault, James’ aunt Rachel Duncan said: “The perpetrators do not realise the ripple effect of their actions. They have not just violently injured James, they have ripped apart our lives.
“I urge anyone who knows anything about the attack to come forward.”
Anyone with information is asked to call 101 or tweet @MetCC quoting CAD 6277/23FEB. Information can also be provided to Crimestoppers, anonymously, by calling 0800 555 111.