London Fire Brigade has advised the public to avoid Whitehorse Road as they work to tackle the blaze.
Control officers received over 30 calls about the fire and eight fire engines and around 40 firefighters were sent to put it out.
The cause of the fire is not known at this point.
The video, filmed by @BANNERWORX and shared on Twitter, shows flames covering balconies coming off of the building as clouds of smoke burst into the sky.
From the video, it appears that the fire has taken hold of three storeys of the building.
A spokesperson for London Fire Brigade said: “Eight fire engines and around 40 firefighters are responding to a flat fire on Whitehorse Road in Croydon.
“Our Control Officers have taken over 30 calls about the fire. People are advised to avoid the area.
“Crews from Croydon, Woodside, Wallington and surrounding stations are in attendance.
“The cause of the fire is not yet known.”
