Twelve fire engines and around 80 firefighters were called to a fire at a commercial building on Old Street in Old Street.
Additional resources were deployed as the fire was affecting a room in the basement of the eight-storey building.
The fire has now been brought under control but crews will remain on scene in order to dampen down. There have been no reports of any injuries at this time.
People are advised to avoid the area whilst the Brigade remains on scene.
The Brigade received the first of five calls about the fire at 2045 and Control Officers mobilised crews from Dowgate, Soho, Shoreditch and surrounding fire stations to the scene. The fire was brought under control by 2232.
The cause of the fire is under investigation.