Georgia issued a statement saying Johnson died early Wednesday in Athens.
Johnson took over as the Bulldogs' starting quarterback in 1971 and led the team to an 11-1 record that included a Gator Bowl victory. He set a Southeastern Conference sophomore rushing record and finished second in the league with 870 yards on the ground, along with 13 touchdowns.
Johnson started two more seasons for the Bulldogs and finished his career with 1,799 rushing yards, the most by a quarterback at that time.
A fifth-round pick by New England, Johnson played 94 games -- including 43 starts -- before finishing his career with the USFL's Boston Breakers. He rushed for a career-high 699 yards with six touchdowns for the Patriots in 1976.