The interest for expeditious separation of photocatalyst from treated water led to the production of magnetic TiO2-graphene oxide (GO) compounds, causing an essential drop in photoactivity. Therefore, the proper proportions of the starting materials produced via sol-gel, and hydrothermal methods were statistically determined according to the mixture design methodology to maximize the photo-degradation of dye under visible light, and solar irradiation. Although the decoration of TiO2-Fe3O4 core-shells onto GO sheets by the sol-gel route via 3-aminopropyltrimethoxysilane resulted in the inappropriate magnetic properties, the hydrothermal method was successfully applied for the fabrication of magnetic compound. The nanocomposite containing the same proportions of GO, and Fe3O4, 4%, not only represented the optimal efficiency, 97%, but could be easily separated by the external magnetic field. The rapid degradation under the sunlight within 20 min was ascribed to a reduction in band gap energy, 1.46 eV, compared to that for anatase.