He played junior hockey for the Brockville Canadiens and the Montreal Junior Canadiens and senior for the Hull Canadiens from 1959 to 1963. His rights belonged to the Montreal Canadiens and he could not crack their powerful lineup. Dennis played in the minors from 1963 to 1968.
In 1968 he was sold to the St. Louis Blues. Dennis managed to get into 12 games for the Blues over the next four seasons, scoring three goals. Otherwise he played in the minors until 1975. He then spent three seasons with the senior Trail Smoke Eaters and retired in 1978.