Four fire engines and 21 firefighters and officers dealt with a flat fire on Tedder Road in South Croydon.
A second floor flat in a three storey block was partly damaged by the blaze. A woman and her son left before the arrival of the Brigade, without injuries.
The cause of the fire is believed to be accidental.
The Brigade was called at 1409 and the fire was under control by 1448. Fire crews from Orpington, Croydon and Woodside fire stations attended the scene.