An exterior mirror system for a vehicle includes exterior rearview mirror assemblies mounted at respective sides of the vehicle. The mirror assemblies include a light module and a camera. The cameras are part of a multi-camera vision system that includes a display device that is operable to display images for viewing by the vehicle driver. The indicator of the light module includes a signal light that is configured to provide light that is observable to another driver of another vehicle who is (i) approaching the vehicle from its rear and/or (ii) overtaking the vehicle in the side lane adjacent to the side of the vehicle at which mirror assembly is mounted. Actuation of the signal light provides (i) light forwardly of the vehicle so that drivers of other vehicles approaching the vehicle may observe the actuated signal light and/or (ii) light laterally with respect to the vehicle.