It was immediately unclear what caused the fire.
The fire broke out early Sunday in the 4300-block of Arthur Avenue.
Firefighters arrived at about 6:30 a.m. to find heavy flames and thick black smoke.
Neighbors told firefighters that there could be a woman inside the home, but firefighters were prevented from initially going in because of the flames.
They eventually found the homeowner dead on the first floor.
Police are investigating. Investigators went door-to-door talking to people on the block.
The woman has been identified to the Cook County Medical Examiner's Office as 53-year-old Susan Colby.
Neighbors said the she lived alone with her dog and two cats. She also loved to work in her yard and cook, they said.
"It's hard to take in yet. We used to talk every once in a while. I would bring her vegetables. She would bring me flowers," said neighbor Kathy Godbout.