An electrostatic discharge (ESD) protection circuit is for protecting an internal circuit electrically coupled to an input/output (I/O) pad. The ESD protection circuit comprises an ESD protection unit, to be electrically coupled to the I/O pad, for enabling release of an electrostatic charge at the I/O pad to a ground terminal. The ESD protection circuit also comprises a voltage detecting unit, electrically coupled to the ESD protection unit and to be electrically coupled to the I/O pad, for detecting the presence of an ESD voltage at the I/O pad and for controlling the ESD protection unit to establish a conduction path between the I/O pad and the ground terminal when the ESD voltage is detected.