Six fire engines and around 40 firefighters tackled a fire at a terraced house converted into flats on Bolton Road in West Hampstead.
Part of a lower ground floor flat was damaged by the fire. There were no reports of any injuries.
Control Officers took the call at 0229 and mobilised crews from West Hampstead, Paddington, North Kensington and surrounding fire stations to the scene. The fire was under control by 0312.
The cause of the fire is under investigation.