The victory gave the Penn State head coach his 409th career victory, bypassing the late Grambling State coach Eddie Robinson to become the winningest coach in NCAA Division I history.
Anthony Fera connected on a 30-yard field goal earlier in the fourth quarter for the Nittany Lions (8-1, 5-0 Big Ten), which won a seventh straight game for the first time since 2008.
The Illini (6-3, 2-3) staged a late comeback try, driving into PSU territory, but a 42-yard field goal attempt by Derek Dimke bounced off the upright as time expired.
Nathan Scheelhaase threw for 63 yards and a touchdown and ran for 89 yards for Illinois (6-3, 2-3).
Notable deaths of 2014 [PHOTOS]