Four fire engines and around 25 firefighters tackled a basement flat fire on Edith Road in Chelsea.
Part of the basement flat was damaged by the blaze.
A woman and two men left the property before the Brigade arrived. The woman was taken to hospital by London Ambulance Service crews
The Brigade was called at 0725 and the fire was under control 0836. Fire crews from Fulham, Battersea, Chelsea and Kensington fire stations were at the scene. The cause of the fire is under investigation.