Four fire engines and around 25 firefighters tackled a fire on Brondesbury Villas in Kilburn.
Part of a ground floor flat, situated inside a semi-detached that has been converted into flats, was damaged by fire.
The Brigade's 999 Control Officers received six calls about the fire.
The Brigade was called at 1035 and the fire was extinguished by 1134. Crews from Paddington, North Kensington, Willesden and Kensington fire stations attended the scene.