A vehicular exterior rearview mirror assembly includes a mounting arm and a mirror head at one end of the mounting arm distal from an attachment portion of the mounting arm that is configured for attachment at a vehicle. A mirror reflective element is fixedly attached at the mirror head. An innermost side of the mirror reflective element is attached at a front side of an attachment plate. The mirror reflective element moves in tandem with movement of the mirror head relative to the mounting arm when the driver of the vehicle operates an electrically-operable actuator. The attachment plate includes wall structure that extends from the front side of the attachment plate and circumscribes and spans the perimeter circumferential edge of the glass substrate and does not encroach onto and does not overlap the front surface of the glass substrate of the exterior mirror reflective element.