Six fire engines and around 40 firefighters attended a fire at a commercial unit on Abbeydale Road in Wembley.
Part of a first-floor plant room was damaged by fire. There were no reports of any injuries.
The Brigade was called at 0258 and Control Officers mobilised crews from Wembley, Hammersmith, West Hampstead and Hendon fire stations to the scene. The fire was brought under control by 0433.
The cause of the fire has been recorded as accidental.