The incident happened in Hillingdon Street, Kennington just after 9.15pm yesterday (April 14).
Officers and London Ambulance Service crews attended and found a man who had been stabbed.
He was pronounced dead shortly after.
Police enquiries are ongoing to locate his next of kin.
We have contacted London Ambulance Service for further information.
A spokesperson for Metropolitan Police said: “On Monday, April 14, at 9.16pm police were called to Hillingdon Street, Camberwell, following reports of a stabbing.
“Officers attended the scene alongside the London Ambulance Service who treated a 21-year-old man for stab injuries.
“Sadly, despite their best efforts, he was pronounced dead on scene. Enquiries are on-going and we are working to locate his next of kin.
“If you saw anything, or have any information then please contact police via 101 stating CAD7392/14APR.
“Alternatively, to remain anonymous you can call Crimestoppers on 0800 555 111.”
