Six fire engines and around 40 firefighters tackled a fire on Waterloo Road in Brent Cross.
A single-storey vehicle workshop was destroyed by fire. Part of a storage unit was also damaged by fire. There were no reports of any injuries.
The Brigade's 999 Control Officers received nine calls about the fire.
The Brigade was called at 0219 and the fire was brought under control by 0422. Crews from Hendon, Willesden, West Hampstead, Park Royal and Finchley fire stations attended the scene.
The cause of the fire is under investigation.