The present disclosure provides communications apparatus and method using an On-off keying (OOK) modulation based low power wake-up protocol suitable for use in IoT devices. The communication method according to an exemplary embodiment includes: transmitting, by a main radio module of a master device, an OOK modulated wake-up radio signal by using a narrow frequency band between an ISM band and a guard band in the ISM band; receiving, by a low power wake-up radio module of a slave device, the wake-up radio signal and to demodulate according to an OOK modulation scheme and awaken a controller of the slave device in a sleep mode; and after the controller wakes up from the sleep mode, transmitting data to be transmitted to the master device, by the controller of the slave device, through the main radio module.