Photoelectrochemical conversion of glycerol into high-value dihydroxyacetone offers a sustainable approach via BiVO₄ semiconductor materials, which manifest highly photoactive properties. However, dihydroxyacetone production poses a limitation due to poor charge transport ability and fast electron–hole recombination of BiVO₄. Herein, we fabricated N₂-annealed BiVO₄ through a facile spin-coating method and an N₂ annealing process. The effect of N2 treatment did not significantly impact the surficial catalytic efficiency, while the bulk efficiency was increased, resulting from changes in oxygen vacancy concentration and carrier density. Owing to improvement in bulk electron–hole separation efficiency, N₂-annealed BiVO₄ at 150 °C exhibited an enhanced photoelectrochemical dihydroxyacetone production rate of 160 mmol m⁻² h⁻¹ at 1.0 V vs. RHE, which was more than 2 times higher than that of pristine BiVO₄. This work establishes a pathway for optimizing semiconductor engineering via post-annealing treatment and provides a modification strategy of BiVO₄ for achieving advanced production of dihydroxyacetone.