The incident happened in New Road near Kings Road just before 9.50pm yesterday (January 29).
Officers and London Ambulance Service crews attended and found a boy who had been stabbed.
He was taken to hospital where his injuries are thought to be potentially life changing.
Police enquiries into the circumstances continue.
A spokesperson for Metropolitan Police said: “Police were called to reports of a stabbing in New Road, Kingston upon Thames on Wednesday 29 January at 9.51pm.
“Officers attended alongside the London Ambulance Service.
“One 15-year-old boy was treated for stab wounds at the scene before being taken to hospital. His injuries are thought to be potentially life changing.
“Enquiries into the circumstances continue.”
