A vehicular trailer sway management system includes at least one rearward-sensing radar sensor disposed at a vehicle and an electronic control unit (ECU). Radar data captured by the at least one rearward-sensing radar sensor is provided to the ECU. With a trailer hitched to the vehicle, the trailer sway management system, via processing at the ECU of the provided captured radar data, determines oblique angles of the trailer relative to the vehicle. As the vehicle tows the trailer, and responsive to monitoring of determined oblique angles of the trailer relative to the longitudinal axis of the vehicle, the trailer sway management system determines sway of the trailer relative to the vehicle. Responsive to the determined sway of the trailer relative to the vehicle, the trailer sway management system at least in part controls operation of the vehicle to manage sway of the trailer relative to the vehicle.