Four fire engines and around 25 firefighters were called to a fire at a restaurant with flats above on Kilburn High Road in Kilburn.
The external ducting from the ground to the fourth floor was destroyed by the fire. There were no reports of any injuries.
The Brigade was called at 0009 and the fire was under control by 0140. Fire crews from West Hampstead, Willesden and Paddington fire stations were at the scene.
The cause of the fire is under investigation.