Born in Jacksonville, Florida and excelling in both sprinting and football, Hayes first became successful as a sprinter. In 1963, he set the World Record in the 100 yard dash at 9.1, earning for himself the nickname of "fastest man alive".
At the 1964 Summer Olympics, in Tokyo, Hayes had his finest hour as a sprinter. First, he won the 100 m by tying the current World Record in the 100 m. This was followed by a second gold medal in the 4 x 100 m relay, which also produced a new World Record. The relay race was also Hayes' last race as a track and field athlete as he permanently switched to football after it.
At the end of that same year, he signed with the Dallas Cowboys, playing as a wide receiver. His first two seasons were most successful, leading the league both times in receiving touchdowns. In 1971, Hayes' last good season with Dallas, he won the Super Bowl, becoming the only person so far to win both an Olympic gold medal and the Super Bowl.
Hayes played one season for the San Francisco 49ers, before retiring.