Four fire engines and around 25 firefighters were called to a fire at a flat on Furlong close in Hackbridge.
Most of a four bedroom flat on the ground floor, of a two-storey building, was damaged in the blaze.
Firefighters wearing breathing apparatus, rescued one man from the property. The man was treated at the scene for smoke inhalation by the London Ambulance Service.
The Brigade was called at 1800 and the fire was under control by 1927. Fire crews from Wallington, Mitcham, Croydon and Norbury fire stations attended the scene.
The cause of the fire is under investigation by the Brigade and Metropolitan Police.