1931 Cal Poly Mustangs football team

The 1931 Cal Poly Mustangs football team represented California Polytechnic School—now known as California Polytechnic State University, San Luis Obispo—as a member of the Northern California Junior College Conference (NCJCC) during the 1931 junior college football season. Led by tenth-year head coach Al Agosti, Cal Poly compiled an overall record of record of 3–5–1, with a mark of 3–2 in conference play, placing third in the NCJCC. The team was outscored by its opponents 152 to 51 for the season. The Mustangs played home games in San Luis Obispo, California.

Cal Poly was a two-year school until 1941. The Mustangs did not field a team in 1930 due to a polio epidemic.