Four fire engines and around 25 firefighters were called to a fire at offices on Watling Street in Bexleyheath.
Part of a store room on the second floor was damaged by the fire. Around 140 members of staff left the building before the Brigade arrived. There were no reports of any injuries.
The Brigade was called at 1019 and the fire was under control by 1136. Fire crews from Bexley, Erith and Plumstead fire stations were at the scene.
The cause of the fire has been recorded as undetermined.