Six fire engines and around 40 firefighters were called to a fire at a launderette on River Road in Barking.
Part of a single-storey warehouse being used as a launderette was damaged by the fire. There were no reports of any injuries.
The Brigade's fire investigators believe the fire was accidental and was caused by self-heating textiles.
A London Fire Brigade spokesperson said: "These types of fires often involve textiles that have been contaminated with oil, most commonly linseed, massage and cooking oil on tea towels, tablecloths and chef whites.
“Sometimes when materials are cleaned, put in tumble dryers and then folded and stacked, the heat from the tumble drying cannot escape. This can result in a high enough temperature allowing it to build up to a point where it smoulders and eventually ignites.
“If you are washing and then drying on a hot cycle, always use the cooling cycle on the tumble dryer so it cools down and allow the heat to dissipate properly, before stacking laundered items together.”
The Brigade was called at 0334 and the fire was under control by 0603. Fire crews from Barking, East Ham, Plaistow, Dagenham and surrounding fire stations were at the scene.