Disclosed is an Ethernet-based vehicle control system and method. The Ethernet-based vehicle control system (method) according to the present invention comprises: a router for connecting a vehicle internal network and a vehicle external network; a vehicle electronic element connected to and communicating with the router; and a third-party module newly mounted on a vehicle to control the vehicle electronic element, wherein the vehicle electronic element includes a Remote Keyless Entry (RKE) module, and the third-party module may piggyback on a signal input into the RKE module by a remote controller through the vehicle external network. According to the present invention, since a third-party module can be freely installed and replaced based on Ethernet, various services related to a vehicle may be realized through a vehicle external network.