The shooting happened in the 300-block of Walker Avenue in Highland Park near the border with Highwood.
The victim, a 30-year-old man, was taken to a hospital in critical condition, police said. Police said his condition was improving on Tuesday morning.
Friday's arrest comes after investigators released images of two persons of interest who were allegedly seen talking with the victim before the shooting.
Police later identified one of those people as a suspect, and a warrant for his arrest was issued. Highland Park police started working with federal and regional partners after an investigation indicated that the suspect had visited a Highland Park residence before leaving the area.
Law enforcement in Fort Wayne, Indiana, responded to a call for service involving the suspect on Friday. Police identified the Lake County, Illinois arrest warrant during their investigation.
The suspect was apprehended and will remain in custody in Indiana on local charges until he is extradited to Illinois and charged in connection with the shooting in Highland Park.
Police said the shooting was an isolated incident, and those involved knew each other.
Officials did not immediately say whether they are still looking for a second person on Friday.
The video in the player above is from a previous report.