The 1991 Youngstown State Penguins football team represented Youngstown State University in the 1991 NCAA Division I-AA football season.
The Penguins were led by sixth-year head coach Jim Tressel and played their home games at Stambaugh Stadium.
They finished the season 12–3.
They received an at-large bid to the I-AA playoffs, where they defeated Villanova, Nevada, and Samford to advance to the National Championship Game, where they defeated Marshall.
This was their first national championship in school history.