Firefighters were called to a fire in a converted terraced house on Landor Road, Brixton, on Monday afternoon.
A small part of a second floor flat was damaged by fire. No one was injured.
Police closed Landor Road for part of the afternoon, with the bus route 322 placed on diversion.
Four fire engines from Dockhead, Brixton, Lambeth and Clapham fire stations went to the scene with 21 firefighters.
The fire brigade was called at 3.15pm and brought the fire under control by 4.20pm. The cause of the fire is being investigated.