Surmounting the selectivity issue of gas sensors and detecting low ppm concentration of gases is highly significant for widespread deployments of sensors to build networks in applications including vehicular emission, fuel-based household appliances, and industrial emissions. Herein, a strategy is proposed to improve the selectivity and sensitivity of the cadmium sulfide (CdS) based sensor via changes in contact material by utilizing different metals. CdS was deposited via the SILAR method on three different glass substrates which have Au, ITO, and Ag contacts, respectively, through which Schottky barrier height (SBH) was adjusted between CdS and metal contact. CdS was thoroughly verified by structural and morphological characterization techniques. As-fabricated devices were tested, and gas sensing results suggest that Au and ITO contacts have significantly superior selectivity towards NO2 and CO gases over other gases. Further, experimental values reveal that sensors can detect up to 0.3 ppm and 1.25 ppm, respectively. Good selectivity can be attributed to the regulation of the SBH. Additionally, as-fabricated devices displayed good long-term stability and short response and recovery times. The present study may provide a rational design for fabricating a high-performance chemiresistive gas sensor for the detection of sub-ppm levels of hazardous gases present in the environment. © 2022 Elsevier B.V.