Four fire engines and around 25 firefighters were called to a fire at a flat on St Peter's Road, Croydon.
Around half of a first floor flat was damaged by fire. Firefighters wearing breathing apparatus rescued one woman via the internal staircase. She was treated at the scene for smoke inhalation and taken to hospital by London Ambulance Service crews.
The Brigade was called at 1701 and the fire was under control at 1751. Fire crews from Croydon, Woodside, and Wallington attended the scene.
The cause of the fire is under investigation by the Brigade and the Metropolitan Police Service.