An offset voltage calibration method is disclosed, which is utilized for calibrating an offset voltage of an electronic device during a calibration period. The offset voltage calibration method includes generating a control signal according to an output signal of the electronic device, counting a count value and generating an offset indication signal according to the control signal, stopping counting and generating a final count value according to a compensation value after the output signal changes state, generating a calibration signal according to the count value or the final count value, and calibrating the offset voltage according to the offset indication signal and the calibration signal.