The Houston Fire Department said crews responded to the Stone Haven at the Galleria Apartments at 6419 Skyline Drive, off Hillcroft and south of Richmond Avenue.
No firefighter or civilian injuries were reported, HFD posted on X, formerly known as Twitter.
The cause is not immediately known, but the fire department urged people to avoid the area due to heavy emergency traffic.
An Eyewitness News crew arrived to a smoky scene and captured flames pouring out of the complex's castle-like corner apartment unit. The number of units impacted was not immediately known.