Four fire engines and around 25 firefighters were called to a fire at a flat on Redbridge Lane West in Wanstead.
Half of a flat on the first floor was damaged by fire.
A man and a woman left the property before the Brigade arrived.
The Brigade was called at 1438 and the fire was under control by 1612. Fire crews from Leytonstone, Leyton, Ilford and Walthamstow fire stations attended the incident.
The cause of the fire is under investigation.