A vehicular rearview mirror assembly includes a mirror reflective element and a touch sensor device disposed behind a portion of the reflective element and operable to sense the presence of a person's finger at a touch zone of the reflective element proximate to the touch sensor device. A backlighting device is disposed behind the touch sensor device and is operable to backlight a portion of the touch sensor device. The touch sensor device includes a touch sensor substrate having a conductive trace established at a patterned conductive zone of the touch sensor substrate. When the backlighting device is activated, light emanating from the backlighting device passes through the patterned conductive zone of the touch sensor substrate and illuminates an icon so that the icon is viewable through the reflective element by a driver of the vehicle when the rearview mirror assembly is normally mounted at the vehicle.