The Rosemont Public Safety Department and several surrounding fire departments responded to the target at 7000 Mannheim Road just before noon on Thursday.
Before first responders arrived, employees tried to extinguish the fire, which they found near the diaper aisle.
Everyone inside the store was able to evacuate, and one was hospitalized.
Officials said at least $1.5 million in merchandise was lost due to fire, water and smoke damage.
The suspect's vehicle was later found in Elk Grove Village.
Officials said 56-year-old Denny Ellis, of Nevada, was charged Sunday with aggravated arson.
The Cook County Sheriff's Department is holding Ellis.
The Rosemont Public Safety Department said anyone affected by this loss who is looking for assistance should reach out to their department.