Eight fire engines and around 60 firefighters tackled a fire at a row of terraced houses in Cowden Road, Orpington.
The fire originated outside and spread into two houses, damaging most of the properties. The exterior of a further two houses were partly damaged by fire.
An older man was suffering from smoke inhalation and treated at the scene by London Ambulance Service crews.
The Brigade was called at 1235 and the fire was under control by 1415. Fire crews from Orpington, Sidcup, Bromley and surrounding fire stations were at the scene.
The cause of the fire has been recorded as undetermined.