Non-enzymatic photoelectrochemical (PEC) glucose sensing using ZnO nanorods (ZnO NRs) is typically constrained to UV excitation, as stoichiometric ZnO possesses a wide band gap. In this work, this UV-only limitation is addressed by deliberately exploiting intrinsic defect chemistry: zinc-vacancy (VZn) defects generated during low-temperature electrodeposition are engineered as the central design knob to activate visible-light PEC glucose sensing—without intentional doping, noble-metal decoration