We demonstrate that the hetero-coupling of SrTiO₃ nanocubes on TiO₂ nanotube arrays and Ti³⁺ dual-doping on both SrTiO₃ and TiO₂ could not only extend their photoresponse from the UV to visible light region, but also facilitate efficient charge separation and transfer between SrTiO_3−x and TiO_2−x. Moreover, their synergistic effects could substantially improve the photoelectrochemical (PEC) performance for water oxidation under visible light irradiation, which is 40 times higher than the PEC capabilities of pristine TiO₂ arrays under the same conditions.