Firefighters tackled a fire at a block of flats on Keswick Road in Putney.
A flat on the second floor of a six-storey block was destroyed by the blaze. One man left the affected property before the Brigade arrived. He was treated at the scene for smoke inhalation by London Ambulance Service crews.
Station Commander Jim Berry, who was at the scene, said: "Crews worked hard to tackle the blaze.
"There were a lot of possessions and clutter inside the flat which made it challenging for firefighters.
"Fortunately the occupant was able to escape, but hoarding means exit routes can become blocked, making self evacuation more difficult.
"Fires can also spread much faster, especially when there are lots of flammable items such as newspapers or cardboard."
The Brigade's 999 Control Officers took seven calls to the fire.
The Brigade was called at 1918 and the fire was under control by 2020. Five fire engines and around 35 firefighters from Wandsworth, Fulham, Battersea and Chelsea fire stations were at the scene.
The cause of the fire is under investigation.