A vehicular electrochromic interior rearview mirror assembly includes a mirror casing and an electrochromic mirror reflective element. At least a portion of a front substrate of the reflective element extends beyond a corresponding portion of a rear substrate of the reflective element to establish a ledge at least partially along the periphery of the reflective element, with no part of the rear substrate extending beyond any part of the front substrate. Electrical connections are made to conductive coatings or layers at the front and rear substrates. The electrochromic interior rearview mirror reflective element includes a concealing layer disposed along a perimeter border region to conceal the presence of the perimeter seal and the electrical connections from view by a driver of the equipped vehicle. The mirror casing provides a bezel-less mirror casing where no portion of the mirror casing overlaps the first surface of the front substrate.