The present disclosure relates to an apparatus for limiting vehicle speed and a method thereof. To prevent a vehicle from exceeding a speed limit to secure safety and improve fuel economy, the apparatus includes: a mode setting device allowing a driver to set any one of a safety mode, a fuel economy mode, and a hybrid mode; a safety speed input device allowing the driver to input a safety speed; one or more processors determining an economical speed on the basis of a driving environment of a vehicle; and a controller limiting a speed of the vehicle on the basis of the safety speed or the economical speed according to a mode set by the driver.