Four fire engines and around 25 firefighters were called to a fire at an industrial unit on Fourth Way in Wembley.
A small part of the ground floor of the detached unit was damaged by the fire. There were no reports of any injuries.
The Brigade was called at 1821 and the fire was under control by 2001. Fire crews from Wembley, Park Royal and Willesden fire stations attended the scene.
The Brigade's fire investigators believe the fire was accidental and was caused by a fault in a compressor.