Four fire engines and 21 firefighters and officers were called to a fire at an office block of seven floors in Belgrave Road, Pimlico.
A small section of the first floor was damaged by fire. Around 300 people left the building before the arrival of the Brigade.
The Brigade was called at 1351 and the fire was under control at 1449. Fire crews from Lambeth, Chelsea, Clapham, and Brixton fire stations attended the scene.
The cause of the fire is under investigation.