A system and method for controlling a motor-driven child seat for a vehicle, may easily allow a seat control unit to perform the power supply and drive control for various electric parts of the motor-driven child seat by connecting between the seat control unit configured to control various electric parts of a vehicle seat and various electric parts of the motor-driven child seat using a connector so that power supply and control signals may be exchanged therebetween when the motor-driven child seat is mounted on the vehicle seat.