Four fire engines and around 25 firefighters were called to a hotel fire on Lombard Road in Battersea.
Part of a hotel room on the second floor of the building was damaged by fire. There were no reports of any injuries.
The fire is believed to have been accidental and caused by a hair dryer that was left on.
A London Fire Brigade spokesperson said: “On arrival, around 15 people were outside the building and there was smoke in the communal areas on the second floor.
“Remember that hairdryers, hair tongs, and straighteners can get extremely hot, so it’s very important to remember to switch them off and leave them to cool on a heatproof surface.”
The Brigade was called at 2349 and the fire was under control by 0047. Fire crews from Battersea, Chelsea, Wandsworth and Clapham fire stations attended the scene.