Four fire engines and around 25 firefighters were called to a flat fire on Forty Avenue in Wembley.
A flat above a shop was destroyed by fire. There were no reports of any injuries.
The Brigade was called at 1406 and the fire was under control by 1520. Fire crews from North Kensington, Willesden, Mill Hill and Northolt fire stations attended the scene.
The cause of the fire has been recorded as undetermined.