Gravelle led the junior OHA with 52 points (30 goals and 22 assists) in 1944-45 while playing with the St. Michael's Majors. He then enjoyed a productive year in the Quebec Senior Hockey League (QSHL) with the Montreal Royals before making his NHL debut the next year. In 1946-47 he scored 16 goals as rookie working on a line with Buddy O'Connor and George Allen on the Montreal Canadiens. "The Gazelle" also chipped in a pair of goals as Montreal drove all the way to the Stanley Cup final.