Cannon first played for the LSU varsity football team as a sophomore in 1957 under coach Paul Dietzel. He played in the halfback position and shared the backfield with Jim Taylor, who was selected as an All-American that year. He also played defensive back and was the team's primary punter. He quickly emerged as a star, scoring twice in early season victories over Alabama and Texas Tech. The Alabama game was the most prolific rushing game of Cannon's college career; he amassed 140 yards with eight carries. Against the Red Raiders, Cannon had five punts for a 40-yard average, completed two of four passes for 31 yards, caught a 59-yard pass for a touchdown, carried thirteen times for 36 yards, and returned a kickoff for a touchdown. Cannon recalled that Texas Tech's focus was solely on Taylor. "They were just wearing Jimmy out", he said. "Of course, they weren't looking for me. They just beat the devil out of Jimmy. With them focusing on Jimmy, I had a great game." Over half a century later, former Red Raiders standout Jack Henry recalled of Cannon: