A vehicular driver monitoring system includes an interior electrochromic rearview mirror assembly and a camera disposed at the interior electrochromic rearview mirror assembly behind and viewing through an electrochromic mirror reflective element into the interior cabin of the vehicle. Supplemental sources of near infrared illumination are integrated into the mirror assembly that, when powered to emit near infrared light, illuminate at least a front seating area within the interior cabin of the vehicle. Presence of the camera is not readily apparent to an occupant sitting in the interior cabin of the vehicle. The interior electrochromic rearview mirror assembly includes a processor that processes image data captured by the camera. The camera at least views a driver-side front seating area of the vehicle and, via processing at the processor of image data captured by the camera, the driver seated at the driver-side front seating area is monitored.