The blaze was reported around 3:45 p.m. Sunday at the woman's two-story residence at 3974 Gamma St., a San Diego Fire-Rescue Department dispatcher said.
The victim was taken to UCSD Medical Center, where she died Monday night, according to the San Diego County Medical Examiner's Office. Her name was withheld pending family notification.
No other injuries were reported.
The cause of the fire remained under investigation.