The incident happened in Tindal Street near Langton Road at around 1pm yesterday (August 10).
Officers and London Ambulance Service crews attended and found a boy who had been stabbed.
Full story: Tindal Street Camberwell stabbing: Boy fighting for life
He was taken to hospital where his condition was assessed as potentially life-threatening and life changing.
Two boys, aged 14 and 15, were arrested on suspicion of grievous bodily harm.
They remain in police custody.
A crime scene remains in place and enquiries are ongoing.
Detective Superintendent Lindsey Billany, of the Met’s local investigation team in Lambeth, said: “My thoughts are with the victim, who is currently receiving treatment in hospital and we are supporting their family.
“This is understandably a concerning incident for the community.
“We quickly arrested two suspects and our officers are working at pace to continue to investigate.
