Six fire engines and around 40 firefighters were called to a fire at a shop with flats above on Marylebone Lane in Marylebone.
Part of the basement and ground floor of the five-storey building were damaged by the fire. Two women left the building before the Brigade arrived and one of them was treated for smoke inhalation and taken to hospital by London Ambulance Service crews.
The Brigade was called at 1244 and the fire was under control by 1345. Fire crews from Kentish Town, Islington, Lambeth, Euston and Kensington fire stations were at the scene.
The cause of the fire is under investigation.