An insulated door lock assembly including a base member with an aperture for the cylinder of a lock. The base member is configured to be mounted to a door around a hole for the door lock. The inner volume of the base member can be filled with an insulating material. A cover member can be coupled to the base member through a hinge joint. The cover member can be configured to switch between an open state and a closed state. A keyway or a thumb turn of the door lock can be accessible in the open state and the keyway or the thumb turn is covered by the cover member in the closed state. An O-ring can also be provided around a periphery of the base member for sealably engaging the cover member to the base member.