Four fire engines and around 25 firefighters tackled a house fire on Vale Road in Sutton.
Part of the ground floor of an end-of-terrace house was damaged by fire. There were no reports of any injuries.
The fire is believed to have been caused by the unsafe disposal of smoking materials.
A London Fire Brigade spokesperson said: “We’d rather you didn’t smoke at all, but if you are a smoker, it’s absolutely vital you ensure your cigarette is completely out when you’ve finished smoking it.
“If you don’t, you risk causing a fire which could not only destroy your home, but also cost you your life.”
The Brigade was called at 1414 and the fire was under control by 1506. Fire crews from Sutton, Wimbledon and New Malden fire stations attended the scene.