Four fire engines and around 25 firefighters were called to a fire at a bedsit on Waterdale Road in Abbey Wood.
Part of the ground floor of a mid-terraced house converted into bedsits was damaged by the fire. Four people left the building before the Brigade arrived. One man was treated on scene for smoke inhalation by London Ambulance Service crews.
The Brigade was called at 0746 and the fire was under control by 0855. Fire crews from Plumstead, Erith and Bexley fire stations were at the scene.
The cause of the fire is under investigation.