The fire started around midnight at the Bala Woods Apartments off Forest North Drive.
When firefighters arrived, heavy smoke was coming from the building.
They kicked in the door of the burning apartment and found the woman inside. They believe she was overcome by smoke.
Crews pulled her from the apartment. She was taken to the hospital, where she later died.
The fire was contained to her apartment. No one else was inside.
Arson says there are no signs of foul play. The cause of the fire is under investigation.