Footage posted on social media showed flames spreading up the Torch Tower, and burning debris falling down.
Civil defence officials have "successfully evacuated" the building and are now working to bring the blaze under control, Dubai's authorities say.
It is not clear what caused the fire in one of the world's tallest buildings.
"No injuries have been reported so far in the Torch Tower fire incident," the government of Dubai's media office tweeted.
The Torch Tower was damaged by an earlier blaze in 2015.