Campbell played wide receiver at Washington State University from 1959 to 1962. During that time he appeared in the Hula Bowl, the College All-Star game, the Coaches All-America game and the East-West Shrine Bowl. Campbell snagged most outstanding player honours in the Coaches and the Shrine Bowl games. He was also awarded the 1961 W. J. Voit Memorial Trophy as the outstanding football player on the Pacific Coast. During his Cougar career he was teamed with fellow CFL Hall of Famer George Reed.
Campbell joined the Saskatchewan Roughriders in 1963 and "Gluey Hughy", as he became known, was a key element of their Grey Cup winning team in 1966. Campbell quit the Roughriders in 1968 to take a position as assistant coach at Washington State but returned for a final year with the Roughriders in 1969. In his six CFL seasons, Campbell caught 321 passes for an average gain of 16.9 yards per reception and scored 60 touchdowns, including 17 TD receptions in 1966. Campbell received western conference all-star honours as a flanker in 1964, 1965, 1966 and 1969. He was a CFL all-star in 1965 and 1966.
Campbell retired as a player after the 1969 season to take up a head coaching job at Whitworth College in Spokane, Washington. During his seven-year tenure as coach, Campbell revived Whitworth's moribund football program and was named conference coach of the year three times.
In 1977, Campbell was named head coach of the Edmonton Eskimos. He took the Eskimos to the Grey Cup that first year but lost 41–6 in a blowout on an icy field against the Montreal Alouettes. It was the last Grey Cup championship game coach Campbell would lose as the Eskimos won the next five Grey Cup games, from 1978 through 1982. Following the 1982 season, Campbell left to become the head coach of the USFL's Los Angeles Express. After one season, the Houston Oilers who were bidding for the services of Warren Moon, hired him to become their head coach and help improve their chances of signing the coveted free agent. He served as head coach of the Oilers for the 1984 and 1985 seasons. In 1986 he returned to the Eskimos as the team's general manager. After 20 years as the head of the Eskimos organization, Campbell announced his retirement effective the end of 2006.