Six fire engines and 35 firefighters and officers were called to a fire at an office block under construction in Clerkenwell Road.
Part of the roof and a stack of insulation at roof level were damaged by fire.
Approximately 50 people left an adjacent building before the arrival of the Brigade. There were no reports of any injuries.
The Brigade was called at 1726 and the fire was under control at 1955. Fire crews from Soho, Shoreditch, Euston, Islington, Dowgate and Lambeth fire stations attended the scene.
The cause of the fire is under investigation.