CuBiO/AgPO was synthesized through a combination of hydrothermal synthesis and an in situ deposition method with sodium stearate as additives, and their textures were characterized with XRD, XPS, SEM/HRTEM, EDS, UV-Vis, and PL. Then, the photodegradation performance of CuBiO/AgPO toward the degradation of diclofenac sodium (DS) was investigated, and the results indicate that the degradation rate of DS in a CuBiO/AgPO (1:1) system is 0.0143 min, which is 3.6 times that in the blank irradiation system. Finally, the photocatalytic mechanism of CuBiO/AgPO was discussed, which follows the Z-Scheme theory, and the performance enhancement of CuBiO/AgPO was attributed to the improved separation efficiency of photogenerated electron-hole pairs.