The teen has been charged with aggravated battery causing great bodily harm, police said.
He was processed at the Joliet Police Department and taken to the River Valley Justice Center.
The injured teen remains in critical condition at St. Joseph Medical Center, police said.
He was found at the Riverwalk Homes Apartments at 366 N. Broadway St. just before 1 p.m. Sunday.
Officers recovered a knife from the scene.
Joliet police are investigating and asked anyone with information to call them at 815-724-3020. Anyone wishing to remain anonymous can contact Will County Crime Stoppers at 800-323-6734 or submit a tip online at crimestoppersofwillcounty.org.