Two males have been arrested on suspicion of murder and taken to south London police stations for questioning.
Police were called at 16:11hrs on Wednesday 27 March by London Ambulance Service to reports of a man in a critical condition in Friar Mews, West Norwood.
Officers and paramedics attended the scene. The male was pronounced dead at the scene at 16:45hrs.
The victim is believed to be in his 20s.
The Metropolitan Police said: “Officers are in the process of informing his next of kin.
“Formal identification awaits; a post-mortem examination will be scheduled in due course. A crime scene remains in place.
“The Homicide and Major Crime Command have been informed and will be leading on this investigation.
“A number of enquiries including review of local CCTV footage and forensic analysis at the scene are in hand.
“Detectives are urging witnesses to speak to police at the scene, call officers, or Crimestoppers anonymously.”
police ask any witnesses and those with information should call police on 101 quoting CAD 5335 or Crimestoppers anonymously on 0800 555 111.
Young people can also pass on information in complete confidence via www.fearless.org