After commissioning, "Kapuskasing" was sent to Bermuda to work up. Upon the vessel's return to Canadian waters, she was assigned to the Western Escort Force as Senior Officer's Ship of escort group W-1. As Senior Officer Ship, the commander of the escort would be aboard her during convoy missions. Primarily used as a convoy escort, the ship remained with the group until the end of hostilities in the Atlantic Ocean. The group was disbanded in June 1945 and she was placed in maintenance reserve at Sydney, Nova Scotia.