Cook spent one season coaching the Sault Ste. Marie Greyhounds of the Northern Ontario Hockey League, in 1956–57, then spent three seasons with the Kingston Frontenacs of the Eastern Professional Hockey League until his retirement in 1961. Cook retired as the most successful coach in AHL history. His seven Calder Cups are four more than anyone else, and his 636 career wins were the most in league history for a half-century (Roy Sommer would pass him in 2016). He was inducted into the American Hockey League Hall of Fame in 2007.