Four fire engines and around 25 firefighters attended a fire on Bedford Hill in Tooting.
Half of a flat on the fourth floor of a sheltered accommodation block was damaged by fire. One man was rescued by firefighters wearing breathing apparatus via an internal staircase. He was taken to hospital by London Ambulance Service to be treated for smoke inhalation.
The Brigade was called at 1626 and Control Officers mobilised crews from Tooting, Clapham and Norbury fire stations to the scene. The fire was extinguished by 1831.
The cause of the fire is under investigation.