The 1991 NCAA Division I-AA football season, part of college football in the United States organized by the National Collegiate Athletic Association at the Division I-AA level, began in August 1991, and concluded with the 1991 NCAA Division I-AA Football Championship Game on December 21, 1991, at Paulson Stadium in Statesboro, Georgia.

The Youngstown State Penguins won their first I-AA championship, defeating the Marshall Thundering Herd by a score of 25−17.

[1] Big Sky Conference – Nevada Gateway Collegiate Athletic Conference – Northern Iowa Ivy League – Dartmouth Mid-Eastern Athletic Conference – North Carolina A&T Ohio Valley Conference – Eastern Kentucky Patriot League – Holy Cross Southern Conference – Appalachian State Southland Conference – McNeese State and Sam Houston State Southwestern Athletic Conference – Alabama State Yankee Conference – Delaware, New Hampshire, and Villanova Only the top four teams in the field were seeded, and thus assured of home games in their first round games.

[2] The location of the final, the Georgia Southern Eagles' Paulson Stadium, had been predetermined via a three-year agreement the university reached with the NCAA in February 1989.

* Next to score denotes host overtime period