The fire broke out just before 4 a.m. on the fourth floor of Hancock Square, a mid-rise apartment complex in Arlington Heights.
Officials say the female victim was 35 years old.
Two police officers were treated for minor smoke inhalation. A firefighter suffered minor injuries.
Arlington Heights fire officials said the fire was contained to one unit.
The cause of the fire is under investigation. Investigators said the fire appears to be accidental and a police detective told ABC7 foul play is not suspected.
Hancock Square resident Bill Winger lives on the fourth floor. He too was treated for smoke inhalation, but is returning to his apartment."
"The smoke alarm went off about 4:30. As has happened in the past, I thought it was a false alarm," said Winger. "I opened my bedroom door and my apartment was full of smoke, so I went to the hallway to maybe go to the fire escape, but there was too much smoke in the hallway, so I went to my balcony. The fire department had just arrived. They said, 'Stay on the balcony, we'll come up and get you when it's safe.' "
Investigators say a few people have been displaced by the fire.