A vehicular vision system includes a plurality of vehicle cameras disposed at a vehicle, a trailer camera disposed at a trailer, and a video display screen disposed at the vehicle and viewable by a driver of the vehicle. When the trailer is hitched to the vehicle, the trailer camera captures image data and provides captured image data to an electronic control unit (ECU). The plurality of vehicle cameras capture image data and provide captured image data to the ECU. An auxiliary camera is detachably attached at an exterior side portion of the trailer. With the auxiliary camera detachably attached at the exterior side portion of the trailer and during a reversing maneuver of the vehicle with the trailer hitched to the vehicle, and responsive to a user input, video images derived from the image data captured by the auxiliary camera are displayed for viewing by the driver of the vehicle.