Police said the crash happened on southbound Route 83 under 55th Street in Clarendon Hills at about 4:45 a.m.
A 30-year-old man was struck by a vehicle while standing or walking in the left travel lane, police said. He was transported to Good Samaritan Hospital, where he died from his injuries.
The Clarendon Hills Police Department and the DuPage County MERIT Major Crash Reconstruction Team are investigating the crash.
Police did not immediately provide further information about the crash.