Harding was one of the top defensive linemen in the CFL from the mid 1980s through the mid 1990s.  Harding started his career with Toronto in 1985 as a free agent signing in May of that year and played 10 seasons with the Argos until becoming a free agent in February of 1995. In those 10 years, Harding received Eastern All-Star status 5 times (1986, 1987, 1988, 1992 and 1994) and in the latter two years he was also an All-Canadian selection. After leaving Toronto, Harding played one season (1995) with the expansion Memphis Maddogs and was a Southern All-Star that year.  With the folding of the American based teams, Harding was a first round pick of the Calgary Stampeders in the dispersal draft.  In his final CFL season with the Stampeders, Harding earned yet another divisional All-Star selection. Harding completed his career with an impressive 105 sacks with his highest single season total set at 16 in 1994.

Harding had one kickoff return for 0 yards in 1987.

Harding had one blocked punt in 1987 and one blocked fieldgoal in 1988.