Four fire engines and around 25 firefighters were called to a flat fire on St Francis Way in Ilford.
Part of a three-roomed flat on the first floor of the building was damaged by fire. Two people left the property before the Brigade arrived. A woman was assessed on scene by London Ambulance Service crews.
The Brigade was called at 0039 and the fire was under control by 0135. Fire crews from Ilford, Barking and East Ham fire stations attended the scene.
The cause of the fire is under investigation by the Brigade and the Metropolitan Police Service.