Four fire engines and 21 firefighter and officers were called to a fire at a house converted into flats in Preston Road in Leytonstone.
Part of a flat on the first floor and part of the roof of the property was damaged by fire.
One woman left the property before the arrival of the Brigade and was taken to hospital by London Ambulance Service crews.
The Brigade was called at 2336 and the fire was under control at 0027. Fire crews from Leytonstone, Leyton and Walthamstow fire stations attended the scene.
The cause of the fire is believed to be accidental.