O'Brien served as the city's mayor from 1969 to 1973.
He went on to become an Associate Judge for the 10th Judicial Circuit until he retired from the bench in 2001.
O'Brien died Friday night at OSF Saint Francis Medical Center.
Visitation will take place Tuesday afternoon, from four until eight, at Wright and Salmon Mortuary.
Funeral mass will be held at Peoria's St. Philomena Catholic Church at 10:30 Wednesday morning.