Although photocatalysis exhibits great prospects in selective catalytic reduction of NO_x (photo-SCR), the principles for the informed design of photo-SCR catalysts are lacking. Herein, based on inert CaTiO₃, we tailor a crystal structure for high-efficiency deNO_x by partially substituting Ca with Ce, and Ti with Fe and Mn. The pristine CaTiO₃ is hard to remove NO in 100–300 °C, while Ce-Fe-Mn doped CaTiO₃ could achieve nearly 100% NO conversion at 135 °C under light irradiation (GHSV = 72000 h⁻¹). The dopants enable CaTiO₃ to activate NO and harvest visible light. By selectively activating gaseous molecules, Ti, Fe, and Mn present significant synergistic effects on accelerating the catalytic cycle of standard SCR. Moreover, it is firmly shown that the photocarriers intensify NO oxidation rather than NH₃-to-NH₂ transformation. This work provides new insights into the structure–activity relationship of perovskite-based catalysts and deepens the understanding of the light-driven mechanism.