A mirror reflective element assembly for an exterior rearview mirror assembly for a vehicle includes a reflective element and a heater pad. The heater pad includes a heater pad substrate having a plurality of electrically conductive traces established thereat. The heater pad substrate is disposed at a rear surface of the reflective element. The electrically conductive traces may include (i) a heating trace that, (ii) first and second electro-optic control traces and/or (iii) accessory control traces. The electrically conductive traces terminate at a connector region of the heater pad substrate. An electrical connector is established at the connector region and has terminals electrically conductively connected at respective terminals of the electrically conductive traces. The electrical connector is formed as part of a back plate of the mirror reflective element assembly and is configured to electrically connect to a single wiring harness of the exterior rearview mirror assembly.