The 2004 Cal Poly Mustangs football team represented California Polytechnic State University, San Luis Obispo as member of the Great West Conference (GWC) during the 2004 NCAA Division I-AA football season.
Led by fourth-year head coach Rich Ellerson, Cal Poly compiled an overall record of 9–2 with a mark of 4–1 in conference play, winning the GWC title.
Cal Poly was a charter member of the newly-formed GWC.
The Mustangs competed as an independent the previous eight seasons.
[6][7] The following Cal Poly Mustang players were selected in the 2005 NFL draft.