Marcel Roy was born in Lac-Mégantic, Québec in April 1942 before moving to Montréal when he turned 20, where he took up cycling. Roy competed in his first road race in 1964, having a short but successful career over the next seven years. His best result came in 1967 when he won gold in the road race at the Pan American Games in Winnipeg. At the Games he also finished sixth with his compatriots in the 100 kilometre team time trial. His performances earned him a place on the Canadian Olympic team for the 1968 Games in Mexico City, competing in both the road race and team time trial. The following year Roy just missed out on becoming the national cycling champion when he placed second in the road race in Calgary. In 1996 he was inducted into the Québec Cycling Hall of Fame.