Herein, we demonstrate a facile and effective method for fabricating Ti³⁺ self-doped SrTiO₃/TiO₂ hetero-photoanodes to fundamentally improve the visible-light-driven photoelectrochemical (PEC) performance. Electron paramagnetic resonance (EPR) spectra confirm the presence of Ti³⁺ in the as-prepared samples. This modified SrTiO_3−x/TiO_2−x sample exhibits remarkably enhanced absorption in visible light region and efficient charge separation and transport. The optimally Ti³⁺ self-doped sample yield a photocurrent density of ∼0.85 mA/cm² at 0.6 V vs SCE under the visible light irradiation, which is almost 20 times higher than pristine TiO₂ at the same conditions. These findings may provide new insights for developing high performance visible light photocatalysts.