Abstract: The present inventive concept relates to electrically-powered, thermal-regulated apparel or heated garments and a controller and related methods of operation thereof. The thermal-regulated apparel item includes a heating assembly having a substrate and shielding layers with an electrical resistance heating element located therebetween. The controller is linked to the heating element and receives measured electrical resistance values from a thermistor or a voltage level of a thermocouple positioned along the heating element and in response, varies an electrical power output to the electrical resistance heating element such that the measured or monitored resistance value of the thermistor, or voltage level of the thermocouple, is maintained relatively constant with respect to a predetermined resistance value or voltage level.