It happened in the Rogers Park neighborhood's 1500 block of West Jonquil Terrace at about 6:15 p.m., police said.
Police said the 2-year-old girl found a handgun and accidentally discharged it, shooting herself in the hand. She was transported to St. Francis Hospital in good condition.
No one is in custody and Area Three detectives are investigating. Police did not immediately provide further information about the incident.