Four fire engines and around 25 firefighters attended a fire at a block of flats on Green Street in East Ham.
A small part of an eight-floor flat was damaged by fire. There were no reports of any injuries.
The Brigade received the first of three calls at 0932 and Control Officers mobilised crews from Leyton, Millwall and surrounding fire stations to the scene. The fire was extinguished by 1039.
The fire is being treated as accidental and believed to have originated from an immersion heater.