Five fire engines and around 35 firefighters were called to a fire at a restaurant with flats above on Edgware Road in Marylebone.
Part of the external extraction system from the ground floor to the roof of the building was damaged by fire. There were no reports of any injuries.
A London Fire Brigade spokesperson said: “On arrival there was smoke coming from the roof of the building and the fire was located in the extraction system.
“Crews worked quickly to bring the fire under control and stop the fire from spreading.”
The Brigade was called at 1618 and the fire was under control by 1736. Fire crews from Paddington, West Hampstead, Soho and Chelsea fire stations attended the scene.
The cause of the fire is under investigation.