| Year: | 1921 |
| Team: | LSU Tigers |
| Sport: | football |
| Conference: | Southern Intercollegiate Athletic Association |
| Short Conf: | SIAA |
| Record: | 6–1–1 |
| Conf Record: | 2–1–1 |
| Head Coach: | Branch Bocock |
| Hc Year: | 2nd |
| Captain: | F. L. "Fritz" Spence |
| Stadium: | State Field |
The 1921 LSU Tigers football team represented the University of Louisiana (now known as Louisiana State University or LSU) as a member of the Southern Intercollegiate Athletic Association (SIAA) during the 1921 college football season. Led by second-year head coach Branch Bocock, the Tigers compiled an overall record of 6–1–1, with a mark of 2–1–1 in conference play, finished tied for ninth in the SIAA. LSU played home games at State Field in Baton Rouge, Louisiana.