Conventional surface-enhanced Raman scattering (SERS) substrates require complicated fabrication techniques and precious nanometals to achieve high sensitivity and reproducibility. Furthermore, since SERS requires the adsorption of analytes on the substrate, the reusability of the substrate is still challenging. Herein, CuO nanorods decorated with gold nanostructure have been developed as a highly sensitive, recyclable, and cost-effective SERS substrate. For the fabrication, CuO nanorods were simply constructed on Cu wire by thermal oxidation at 500 °C. Then, Au nanostructures were decorated on the CuO nanorod's surface by UV photoreduction approach. The prepared Au–CuO substrate enabled the identification of methylene blue at a concentration as low as 0.1 pM. Furthermore, the SERS activity of Au–CuO substrate was still maintained at approximately 80% after 3 times recycling by illuminating the substrate with UV irradiation. The long-term surface stability of the substrate was also evaluated, and the decrease of SERS signal was only 4.7% after three days of exposing the substrate to the ambient environment.