Born in Weyburn, Saskatchewan, Giroux starred in junior with the local Weyburn Red Wings and the Swift Current Broncos from 1967 to 1971. He then spent a year playing senior hockey with the WIHL's Kimberley Dynamiters before signing as a free agent with the St. Louis Blues in 1972. He was assigned to the Fort Worth Wings of the CHL and recorded 47 points on the way to being named to the league's first all-star team.