Flames badly damaged an upstairs bedroom of Sir Anthony Hopkins' four-story brick row house, according to a newspaper report.
No one was in the house at the time, the Sun said in Monday's editions.
Firefighters said the actor's wife returned home as they fought the blaze in the Knightsbridge district of London. It was not immediately known where Hopkins was. The actor lives mostly in Los Angeles.
The bedroom in which the blaze broke out was badly damaged by fire but the rest of the house was intact despite a small amount of smoke damage, said a spokesman for the London Fire Brigade.