An interior rearview mirror system of a vehicle includes an interior rearview mirror assembly having an electro-optic reflective element. The reflective element includes (i) an electro-optic active region where an electro-optic medium is disposed and is bounded by a perimeter seal and (ii) a user input region outboard of the electro-optic active region. At least one backlit user input, such as a capacitive touch sensor, is disposed at the reflective element at the user input region and outboard of the perimeter seal and the electro-optic medium. A control is operable to determine a location of a touch or proximity of a finger of a user that is at or near the first surface of the front substrate at the user input region, and the control generates an output signal indicative of a determined touch or proximity of a finger of a user.