Four fire engines and around 25 firefighters were called to a fire on Hugh Street in Pimlico.
Most of a ground floor room in a four-storey hotel was damaged by the fire. There were no reports of any injuries.
Station Commander Jon Singleton, who was at the scene, said: "The fire broke out in a ground floor hotel room.
"Around 25 people left the building before the Brigade arrived.
"Firefighters wearing breathing apparatus carried out a search of the hotel and fortunately, there were no people involved and no reports of any injuries."
The Brigade was called at 1235 and the fire was under control by 1330. Fire crews from Soho, Chelsea and Kensington fire stations were at the scene.
The fire is believed to have been involved an electric fan.