Four fire engines and around 25 firefighters were called to a fire at a restaurant with flats above on Thayer Street in Marylebone.
Crews tackled a small fire in the basement of the four-storey building. There were no reports of any injuries.
The Brigade was called at 0150 and the fire was under control by 0225. Fire crews from Euston, Paddington, Kensington and Lambeth fire stations were at the scene.
The cause of the fire is under investigation.