 With longtime business partner Leo Dandurand, Cattarinich became prominent in the Montreal tobacco wholesaling business, but it was their popularization of the Parimutuel betting system at local tracks that provided their greatest commercial success.With the re-introduction of race track betting in the United States after World War I, the pair, known popularly as "Catta-Léo", extended their activities to racetracks in Chicago, Jefferson Parish, Louisiana, New Orleans, and others in St. Louis and further afield.In 1921, along with Dandurand and Louis Létourneau, Cattarinich purchased the Montreal Canadiens of the National Hockey League from the estate of George Kennedy for $11,000.