The Fire Brigade were called to a block flats on Upper Tulse Hill just after 12pm.
Four fire engines and 21 firefighters and officers from Brixton, West Norwood and Clapham fire stations attended the incident.
Firefighters wearing breathing apparatus led residents to safety, fortunately no-one was injured.
Chris Hawkswell from the London Ambulance tweeted: “We are at a fire in #Brixton with duty officer Andy on standby with @LondonFire & @LambethMPS. Currently no patients.”
Part of a ground floor flat in the block was damaged in the blaze and the cause of the fire is under investigation.
The Brigade was called at 12.13 pm and the fire was under control at 13.01pm.