Police were called at 6.30pm on Wednesday, 1 June to Henderson Close, NW10 to reports that a male had been stabbed.
Officers and the London Ambulance Service attended and a found a man, believed to be aged in his mid-20s, injured in the street. Despite their efforts he was pronounced dead at the scene at 19:15hrs.
Officers are in the process of contacting his next of kin.
A post-mortem examination will be held in due course.
A crime scene is in place and a number of roads are closed to traffic.
Detectives from the Specialist Crime Command have been notified.
There have been no arrests and enquiries continue.
Anyone with information is asked to contact police via 101 quoting reference CAD 5882/01Jun. To remain anonymous call Crimestoppers on 0800 555 111.