Police said the hit-and-run crash happened around 5 p.m. at 112th and Stewart in the city's Roseland neighborhood.
The girl was running on Stewart when a sedan struck her.
Officers said after the crash, the sedan's female driver jumped out of the car and fled the scene.
The victim is being treated at Christ Hospital.
Police are still looking for the driver.
CPD's Major Accidents Investigation Unit is investigating.