Police were called at 4am on Monday, 23 September after a man was found injured outside a shop in The Broadway, Southall.
The victim, thought to be aged in his early 20s, was taken to hospital suffering from a stab injury; he we was pronounced dead at 5.26am.
Officers are working to inform his next of kin.
Formal identification awaits and a post-mortem examination will be scheduled in due course.
Enquiries into how the victim sustained his injuries are ongoing.
At this early stage there have been no arrests.
Officers from Specialist Crime have been informed.
A large crime scene is in place.
Anyone who has information that could assist police is asked to call 101 ref CAD 876/23 Sept.