In his NHL career, he had the role of enforcer and retired with 42 goals, 110 assists and 1,264 penalty minutes in 490 regular season games.

His contemporaries for most of his career were the Hall of Famers King Clancy and Hap Day, who were the best defensemen on his team.

He retired as the league's all-time penalty minute leader, a mark he held until Ted Lindsay broke it in the late Fifties.

After retiring from hockey in 1940, Horner lived in Florida, and Toronto, where he became involved in business ventures for several companies including the Elias Rogers Fuels Limited and the Canada Coal Company Limited, where he later became President before retiring.

On February 13, 1999, he was involved in the opening and closing ceremonies of the final game at Maple Leaf Gardens.