In 1965, the Pittsburgh Steelers signed Leigh as an undrafted free agent, after then commissioner Pete Rozelle made a special ruling, allowing him to become the first and only NFL player to be signed directly out of high school.
Realizing Charlie needed development Pittsburgh moved him to the Pennsylvania Mustangs of the NAFL which was a minor league team.
Charlie also led the team in kickoff and punt returns while leading them to the conference championship.
Leigh was a part of the taxi squad of the Cleveland Browns from 1966 to 1967, while also playing for the Panthers.
[6] He would later be cut and re-signed by the Browns, but received little time at running back and did not carry the ball the entire season, although he did catch two passes.
In 1970, he played 8 games for the Ottawa Rough Riders of the Canadian Football League, before being released.
He couldn't play in Super Bowl VI against the Dallas Cowboys, because of a separated right shoulder he suffered in the AFC championship game against the Baltimore Colts.
[8] Leigh became the primary punt returner for the famous 1972 Miami Dolphins team that had a perfect season and won Super Bowl VII.
[9] Leigh got to play in Miami's 14–7 Super Bowl victory over the Washington Redskins, but did not have any carries or returns.
[10] Leigh had one of his most productive seasons in 1973 for the Dolphins, another Super Bowl championship team.
The 5.2 yards per carry average was better than several of his more celebrated teammates, including Hall of Famer Leroy Kelly (4.2), Hall of Famer Larry Csonka (4.3), 3 time Pro Bowler Mercury Morris (5.1) and 2 time Pro Bowler Jim Kiick (3.7).