Following Millen's retirement from the NHL, he began doing commentary for the Ottawa Senators, Hockey Night in Canada, and Sportsnet. He shared the booth with other icons such as Don Cherry, Ron MacLean, Bob Cole, Harry Neale, and Jimmy Hughson.
Millen's success in the NHL was quite historic, but his voice in the booth reached the Stanley Cup Finals twelve times, twelve NHL All-Star Games, three Olympic Games, and two World Cup of Hockey's.