The blaze happened late Friday night near 50th and Carpenter in the city's Back of the Yards neighborhood.
Several children sleeping in the attic managed to jump out a front window to safety, but 12-year-old Tatiana Joseph was found dead near an attic closet.
Investigators say the fire was caused by "careless use of smoking materials."
PHOTOS: Girl, 12, killed in South Side fire that injured 8 others