Selective production of value-added platform chemicals from renewable biomass feedstocks and their derivatives has attracted tremendous attention with high potential in addressing global problems of energy and sustainability. In this work, a lead-halide perovskite (MAPbBr3, MA = methylammonium) is utilized as a photocatalyst for selective oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-diformylfuran (DFF) using atmospheric O2 upon visible-light irradiation. Under minimally optimized conditions, the photocatalytic conversion of HMF in acetonitrile solvent reaches 100% with a DFF selectivity of over 90%, achieving an overall furanic carbon yield of over 96%. A detailed catalytic mechanism was proposed based on various spectroscopic and experimental results, revealing that the atmospheric O2, photogenerated electrons (e–), holes (h+), •O2–, and 1O2 species together play crucial roles in the effective and selective photo-oxidation of HMF to DFF. In addition, our present photocatalytic system is also applicable for photo-oxidation of benzyl alcohol with approximately 100% conversion and benzaldehyde selectivity, providing insights for future exploration of the present catalytic system.