The present disclosure proposes a fully integrated accurate LED output current controlling circuit and method, which can be seamlessly combined with true PWM dimming. The current controlling circuit has an auto zero function in the light-emitting diode driver to eliminate offsets caused by the system, process variations, parasitic effects, dimming and so on in an LED driver application, and thus is capable of controlling the LED current with high accuracy. Moreover, the driver of the present disclosure does not require the use of external components such as an external resistor to regulate current accuracy.