Police were called shortly before 5am on Saturday, 2 October, to reports of a male shot in Birdhurst Road, Croydon.
Officers attended along with the London Ambulance Service. Despite the efforts of the emergency services, a 35-year-old man was pronounced dead at the scene. His next of kin have been informed.
A post-mortem examination will be arranged in due course.
A murder investigation has been launched, led by DCI Katherine Goodwin of Specialist Crime.
DCI Goodwin said: “My thoughts are with the family of the victim. They will be supported by specialist officers.
“Although our enquiries are at a very early stage, I believe the victim may have attended a house party which continued through the early hours of Saturday morning, near to the scene of the shooting in Birdhurst Road, Croydon.
“Officers would like to speak to anyone who was at that party. Even if you do not think you saw or heard anything significant, please contact police if you were there.
“I also want to appeal for any witnesses, anyone with information or anyone who may have relevant dashcam or other footage to please get in touch.”
There has been no arrest at this early stage.
To provide information, please call the incident room 020 8785 8244. To remain anonymous, you can contact the independent charity Crimestoppers.