A key interlock control system may include a parking position switch unit configured to detect whether a gearshift lever is located in a parking position; an ignition switch unit configured to be electrically connected to at least a power terminal for supplying electrical power to at least an electric or electronic component by manipulation of an ignition key; and a control unit configured to receive a signal from the parking position switch unit and a signal from the ignition switch unit and to determine whether the ignition key is to be locked by a key interlock unit based on the signals of the parking position switch unit and the ignition switch unit.