Cannon was selected as the first overall pick in the 1960 NFL Draft and as a first-round territorial pick in the 1960 American Football League draft, resulting in a contract dispute that ended in court. Cannon played in the AFL for the Houston Oilers and Oakland Raiders before ending his football career with the Kansas City Chiefs of the NFL. He began his professional career as a halfback for the Oilers. A two-time AFL All-Star, Cannon led the league in rushing and all-purpose yards in 1961. He was named the most valuable player of the first two AFL championship games, which were won by the Oilers. He was moved to fullback and later tight end after being traded to the Raiders, with whom he won another league championship in 1967. That season, he played in the second AFL–NFL World Championship game, retroactively known as Super Bowl II, in which his team was defeated by the Green Bay Packers.