In recent times, there has been a growing interest among materials communities in functional nanomaterials. This paper aims to explore the fundamental advancements in the role of Cadmium sulfide (CdS) in photoelectrochemical water splitting, CO2 conversion, photocatalytic H2 conversion, photovoltaic devices, and gas sensors. Additionally, we provide a summary of key points and propose avenues for advancing research on CdS‐based composites.