Disclosed are a method for transmitting and receiving data through a relay in a wireless communication system and an apparatus therefor. Specifically, a method for transmitting and receiving, by a remote user equipment (UE), data to and from a network through a relay UE in a wireless communication system includes: recognizing that small data to be transmitted to the network is generated; performing a discovery procedure through the relay UE and a PC5 interface; and transmitting a PC5 message including the small data to the relay UE when it is verified that the relay UE has an ability to transmit the small data to the network in the discovery procedure, in which when it is indicated that the relay UE supports a small data transmitting procedure by a PC5 discovery message received from the relay UE in the discovery procedure, it may be determined that the relay UE has the ability to transmit the small data to the network.