Beloit Police and Fire Units were called to the home at 2014 Sun Valley Drive around 6:00 a.m. Friday.
They were able to quickly put out the flames, but did find the woman's body inside. She has been identified as Colleen S. Montgomery.
Capt. William Tyler, from the Beloit Police Department, says details of the cause of the fire and the woman's death are sketchy at this time.
He says the police are investigating who else might have lived in the home as well as if anyone was in the area at the time of the fire who might have more information.
The incident remains under investigation.