An interior rearview mirror assembly for a vehicle includes a mirror casing and a mirror reflective element having a first glass substrate and a second glass substrate with an electro-optic medium sandwiched therebetween and bounded by a perimeter seal. A front substrate has a rounded perimeter edge region that has a radius of curvature of at least 2.5 mm and that spans between a front side and a rear side of the front substrate. The rear side of the front substrate is adhesively attached at a first surface of the first glass substrate of the mirror reflective element. The rounded perimeter edge region of the front substrate is exterior the mirror casing and provides a smooth continuous transition between the front side of the front substrate and a side wall surface of the mirror casing.