An interior rearview mirror assembly includes a mirror reflective element having a glass substrate with planar front and rear surfaces. A plastic molding is circumferentially disposed about a circumferential edge of the glass substrate without overlapping onto the front surface of the glass substrate. The plane of the front surface of the glass substrate is generally flush with an outermost part of the plastic molding, which provides a curved rounded transition from the front surface of the mirror reflective element to a side surface of the plastic molding. The plastic molding includes at least a portion of a mirror housing of the interior rearview mirror assembly. The plastic molding includes structure for attaching a rear mirror casing cap portion thereat. With the rear mirror casing cap portion attached at the structure, the rear mirror casing cap portion at least partially encases a rear portion of the plastic molding.