DeMarco started his National Hockey League career with the Chicago Black Hawks.

DeMarco signed with the Chicago Black Hawks in 1938, splitting time with the Providence Reds of the International-American Hockey League.

In the 1942–43 season, DeMarco was loaned to the Toronto Maple Leafs, then traded to the Boston Bruins.

It was the end of his NHL career, but DeMarco played for Cleveland, the Washington Lions and Buffalo Bisons for another five years.

In 1952, DeMarco returned to his hometown and played for the senior North Bay Trappers for several more years.