An automatic flush actuation apparatus, which is incorporated with a flushing system having a water inlet, a water outlet, and a water chamber communicating therebetween, that includes a valve member being moved by a flush lever for releasing the water pressure within the water chamber to allow the water passing from the water inlet to the water outlet, and a sensor-operated powering assembly including a relief valve provided at the valve member for controlling the water flowing to the water outlet and an actuator arranged in such a manner that while sensing a presence of a user of the flushing system, the actuator is driven to move the relief valve to an opened position for releasing the water pressure within the water chamber to allow the water passing to said water outlet.