Four fire engines and around 25 firefighters tackled a fire on Stoke Newington High Street in Stoke Newington.
Most of a studio flat on the second floor of a three-storey building containing a shop with flats above was damaged by fire. One man left the property before firefighters arrived. He was taken to hospital by London Ambulance Service crews suffering from smoke inhalation. Firefighters wearing breathing apparatus rescued a cat.
The Brigade's 999 Control Officers received five calls about the fire.
The Brigade was called at 0459 and the fire was under control by 0549. Crews from Stoke Newington, Homerton and Islington fire stations attended the scene.
The cause of the fire is under investigation.