A rear lateral blind-spot warning system for a vehicle includes a sensor configured to sense position information and movement information on an external obstacle, a determiner configured to determine the type of the external obstacle located in a rear blind spot or a lateral blind spot of the vehicle based on the position information and the movement information sensed by the sensor, a setter configured to set a rear lateral blind-spot warning range or a rear lateral blind-spot warning time based on the type of the external obstacle determined by the determiner, and a controller configured to control rear lateral blind-spot warning operation based on the rear lateral blind-spot warning range or the rear lateral blind-spot warning time set by the setter.