The incident happened in Clydesdale Road at 2.05am today (November 20).
Firearms officers and London Ambulance Service crews attended and found a man injured.
He was taken to a west London hospital where his injuries were assessed as not life threatening.
His next of kin have been informed.
No arrests have been made following the incident.
A spokesperson for Metropolitan Police said: “Detectives are investigating a shooting in west London.
“Police were called at 02:05hrs on Monday, 20 November to reports of a shooting in Clydesdale Road W11.
“Specialist firearms officers were among those responding.
“Officers found a man in his 20s with gunshot injuries. He was taken to a west London hospital, where he remains.
“His condition is not life-threatening. His next of kin have been informed.
“At this early stage there have been no arrests.
“Anyone who has information, video or images that could help police should call 101 ref CAD 454/20 Nov.
“To remain 100% anonymous contact the independent charity Crimestoppers on 0800 555 111.”
A spokesperson for London Ambulance Service said: “We were called today (20 November) at 2:09am to reports of an incident at Clydesdale Road, W11.
“We sent a number of resources to the scene, including an ambulance crew and a medic in a fast-response car.
“We also dispatched London’s Air Ambulance, consisting of a trauma team in a car.
“We treated a man at the scene, before taking him to a major trauma centre.”