Design and development of a low-cost, low-power, miniature, highly sensitive, and selective carbon dioxide (CO2) sensor is an active research area due to the rapid rise of CO2 closed to 408 ppm in the atmosphere because of the industrial revolution. This research proposes a highly sensitive planar interdigital sensor coated with graphene oxide (GO) to induce selectivity towards CO2 . The performance of the sensor has been analysed with various temperatures, humidities, and different CO2 concentrations. The developed sensor has been characterised using Electrochemical Impedance Spectroscopy (EIS). The calibration standard has been developed for a range of CO2 concentrations from 400 ppm to 4000 ppm. The standard gas chromatography (GC) method is used to validate all the results. The temperature and humidity compensation mechanisms are also included to improve the detection ability for determining the CO2 gas concentration from unknown gas samples. Repeatability, reproducibility, stability, cross-sensitivity, response, and recovery time are also tested. The obtained results are highly encouraging to develop a low-cost smart CO2 gas sensing system for both indoor and outdoor environmental applications.