The 1921 college football season had no clear-cut champion, with the Official NCAA Division I Football Records Book listing California Golden Bears, Cornell Big Red, Iowa Hawkeyes, Lafayette Leopards, Washington & Jefferson Presidents, and Vanderbilt Commodores as champions. Only California, Cornell, Iowa, and Lafayette claim national championships for the 1921 season.

The 1921 Cornell Big Red football team was an American football team that represented Cornell University as an independent during the 1921 college football season. In its second season under head coach Gil Dobie, Cornell compiled an 8–0 record, shut out five of eight opponents, and outscored all opponents by a total of 392 to 21, culminating in an invitation to participate in the 1922 Rose Bowl game. The 1921 season was part of a 26-game winning streak that continued until October 1924 and included national championship claims for 1921, 1922, and 1923.