On January 31, 1905, Seibert signed with the professional Canadian Soo of the International Professional Hockey League (IPHL) for $30 per week and board. He only played one game with the Soo, suffering a season-ending broken leg in his first game against Calumet on February 2, 1905. Seibert later played professional hockey for London, Ontario and Guelph in the Ontario Professional Hockey League. The Royals played in the OPHL during the 1908–09 season. He also played professional in the Northwestern Michigan League.