A light output control method for a lighting system is provided. The lighting system includes a plurality of sensors and a light-emitting unit. The light output control method includes steps of: sensing a motion of an object within the sensing ranges of the sensors at different time spots, thereby generating multiple sensing values; obtaining a sensing sequence data according to the sensing values indicating the motion of the object sensed by the sensors; controlling the light-emitting unit to perform a light output control operation if the sensing sequence data complies with a predetermined condition.