The fire broke out in a three-storey building on Battersea Park Road just before 2:30pm yesterday.
Two flats on the second floor and part of the roof were damaged.
No one was injured after smoke alarms alerted occupants, who evacuated safely.
A London Fire Brigade spokesperson said: “Two occupants inside one of the flats were alerted to a smoke alarm sounding. They then found smoke coming from a bedroom and evacuated the building and called 999.
“This incident highlights just how important it is to have working smoke alarms fitted, on every level of your home. It allowed the occupants to escape unharmed whilst the fire was still relatively small.
“Smoke alarms give the earliest possible warning when a fire starts and we would urge everyone to make sure they have one fitted in every room where a fire can start except kitchens or bathrooms where heat alarms are more appropriate.”
People in the area were advised to keep their windows and doors closed at the height of the fire due to smoke travelling from the incident.
