Born in Morrisburg, Ontario, Mallen played one season with Cornwall of the Federal Amateur Hockey League (FAHL) before turning professional with the Calumet Miners of the International Professional Hockey League (IPHL) in 1904. His first season, he scored 38 goals in 24 games to establish a goal-scorer's reputation. He left the IPHL because of the rough play in December 1905, returning to the FAHL, although he returned to Calumet for one final season in 1907. He played in 1907-08 with Toronto of the Ontario Professional Hockey League and the Montreal Hockey Club, then played another season in the United States for the Pittsburgh PAC of the Western Professional Hockey League (WPHL). Mallen continued his team-hopping ways, playing in Ottawa from December 1909 until December 1910, then the Qu