The man was discovered by police on Thursday morning suffering from multiple head injuries.
Police were called at 07:44 am on February 19 with reports of a seriously injured man in Bannister Close, SW2.
Arriving at the scene officers discovered a large pool of blood.
After a search of the area they found the injured man and he was taken to hospital where he remains in a critical condition.
Lambeth Police have launched an investigation but have made no arrests so far.
Detectives are asking anyone with information to call 020 8649 2189 or, if they want to remain anonymous, to call Crimestoppers on 0800 555 111.