Many neuroscience studies in rodents are limited spatially and temporally by the use of tethered devices, head-fixed recordings or battery-powered telemetric implants. When subtle behavioural readouts are needed, protruding implants may affect neurophysiological and psychobehavioural parameters. We have successfully deployed and continue to develop ADInstruments’ KAHA Wireless Optogenetics Biopotential Telemeter which allows simultaneous user-defined optogenetic stimulation (460nm) and continuous electroencephalogram recording at 2kHz. Powered by inductive charging to remove the limitations of battery-life and allowing for higher sampling rates, this device enables long-term, uninterrupted data collection and intervention with more data gathered from fewer animals. ChR2 (H134R) was expressed in the somatosensory cortex of male Wistar rats via AAV8. After two weeks- with rats reaching 175g, a KAHA telemeter was implanted intraperitoneally with the optic fibre positioned over the left somatosensory cortex and 2 skull screws positioned at AP:-3, ML:-2.5/+2.5 and AP:-3 (from bregma) to record cortical EEG. Across a range of stimulus parameters, cortical rhythms at 2, 5, 10 and 20 Hz were entrained over multiple recording sessions in awake rats (6) and anaesthetised rats (4). We also present a telemeter implantation method with telemeter and head-gear entirely enclosed subcutaneously, with explant and fibre-connectorisation protocols to increase reusability. Overall, this study provides the first in-animal validation of this device for entraining cortical rhythms using the onboard optogenetics stimulation capability, showing it to be a potentially powerful tool in chronic, longitudinal optogenetic experiments in rats, affording significant ethical benefits and removing behavioural confounds to the experiment.