A mesoporous SiO₂/Cu₂O–graphene composite, a novel material, was successfully synthesized using a self-assembly method with tetraethyl orthosilicate (TEOS). During the reaction, Cu₂O and silica nanoparticles were loaded on the graphene sheets. The mesoporous structure, morphology, pore diameter, pore volume, and surface area of the mesoporous SiO₂/Cu₂O–graphene composite photocatalysts were obtained via X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analysis, transmission electron microscopy (TEM), Raman spectroscopy, ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS), X-ray photoelectron spectroscopy (XPS), FT-IR spectra, nitrogen adsorption/desorption isotherms using the BET and BJH method and photocurrent analyses. The photocatalytic degradation of rhodamine B (RhB), methylene blue trihydrate (MB), and reactive black B (RBB) in an aqueous solution under visible light irradiation was observed via UV spectrophotometry after measuring the decrease in their concentrations. The mesoporous structure of silica nanoparticles with a large surface plays a major role in the increased photodegradation as well as in the decomposition by the catalysts. Through recycling experiments, we conclude that the mesoporous SiO₂/Cu₂O–graphene composite had good stability during photocatalysis under visible light irradiation. The mesoporous SiO₂/Cu₂O–graphene nanocomposite is expected to become a candidate material for photodegradation with excellent performance.