The Chicago Black Hawks signed Bentley to a contract in the fall of 1939. He had previously been placed on the protected list of the Montreal Canadiens, meaning they were the only NHL team eligible to sign him to a contract. They subsequently dealt his NHL rights to the Boston Bruins for Vic Myles. When he and brother Max went to Boston for a tryout camp, Bruins' owner Art Ross declared them "among the worst amateurs to come to my camp". However, by the time Chicago signed him, Bentley had established himself as one of the top forwards on the prairies.