The 2021 Northwestern State Demons football team represented Northwestern State University as a member of the Southland Conference during the 2021 NCAA Division I FCS football season.

Led by fourth-year head coach Brad Laird, the Demons compiled an overall record of 3–8 with a mark of 3–5 in conference play, tying for fourth place in the Southland.

Northwestern State played home games at Harry Turpin Stadium in Natchitoches, Louisiana.

The Southland Conference released their preseason poll in July 2021.

[1] In addition, nine Demons were chosen to the Preseason All-Southland Team.