Photodetectors (PDs) devices, which convert light energy into electrical signals, have widespread applications in electronic communication, industrial electronics, medicine, and the automobile industry. Photodetectors can be developed with exceptional photoelectric properties, such as tunable bandgaps and excellent carrier migration behavior, making them promising devices for optical detection applications. Graphene, a two-dimensional (2D) material, is one of the most appropriate materials for PDs fabrication due to its excellent optical and electrical properties, including a tunable bandgap and superior carrier mobility. Therefore, graphene-based PDs exhibit ultra-fast response/recovery times and a broad spectral response covering the UV–Visible–IR range. In the present work, RGO/CuO hybrid nanostructure was utilized to fabricate a low-cost and efficient PD, aimed at investigating its photoresistive response under UV exposure. The developed PD showed the most significant changes in resistance when exposed to UV, with a response of approximately 43%. The photodetector was checked repeatedly for five ON/OFF cycles of UV exposure at a regular interval of 90 s, wherein a stable response was recorded. Moreover, the photodetector exhibited good stability under varying temperature and relative humidity (RH) values. Hence, these results indicate that RGO/CuO hybrid nanostructure can be considered as a potential structure for its practical use in various photodetector-based industrial applications.