It happened at Princeton Place Apartments, which are senior living apartments in the 400 block of West Third Street.
Princeton Police Chief Tyrone Sutton said the neighbor called around 6:30 p.m. to report that the blinds in the woman's apartment looked charred and dark.
Authorities said a family member broke one of the apartment's windows in an effort to try and save 75-year-old Iris Toleito.
"Big crowd of people near the apartment right in front, basically they were shouting, screaming, wondering what was going on," Sutton said. "There was some smoke coming out of the house."
When emergency workers were able to open the door to the apartment, they found Toleito on her bed near the front of the apartment. She was pronounced dead on the scene. Crews also found her cat and were able to rescue it.
Officials said the fire was contained to the bedroom. No other units at the complex were affected.
The cause of the fire has not been determined, but officials have ruled out electrical and foul play.
"Right now what we are basicly trying to do is ... an investigation into what took place, trying to figure out what happened," Sutton said. "We do know that the stove was not on, so we ruled that out, but at this time we are not sure exactly what started the fire."
Meanwhile, Toleito's body has been taken to the state medical examiner's office for an autopsy.
Princeton is about 40 miles southeast of Raleigh.