Four fire engines and around 25 firefighters were called to a small fire at a data storage centre on Greenwich View Place in the Isle of Dogs.
A small part of a supply room on the third floor of the building was damaged by fire. There were no reports of any injuries.
The Brigade was called at 0831 and the fire was under control by 0930. Fire crews from Millwall, Poplar, Shadwell and Whitechapel fire stations attended the scene.
The cause of the fire is under investigation.