Harrison came to the Calgary Stampeders in 1964 as a linebacker, but was converted to tight end . At that position, Harrison became a Western conference all-star 6 times (1965, 1967–1971) and CFL-All Star 3 times (1968, 1969, 1970). In 1968, he led the CFL with 1,306 yards receiving. In 1969 and 1970, Harrison led the Western conference in pass receptions with 68 and 70, respectively, and tied for the lead in 1971 with 70 catches.
For his pass catching and blocking abilities as one of the premier tight ends of his era, Harrison was inducted into the Canadian Football Hall of Fame in 1993 and his number (No. 76) retired as a member of Calgary.