A low-cost, low-power planar interdigital carbon dioxide (CO2) sensor is proposed in this research. A well-known dielectric material graphene oxide (GO) is used as a coating material to induce selectivity towards CO2. The proposed sensor has been characterized and calibrated for detecting various CO2 concentrations, temperature and humidity. A temperature and humidity compensation mechanism is also included for improving the accuracy in CO2 concentration measurement in unknown samples. The reproducibility, repeatability, cross-sensitivity, stability, response, and recovery time test results are promising for developing a cost-effective, smart CO2 gas monitoring system for both indoor and outdoor environments.