Photocatalytic oxidation of volatile organic sulfur compounds under practical indoor lighting is restricted by low light intensity, surface sulfur accumulation, and formation of disulfide byproducts rather than selective oxidation toward CO₂ and oxidized sulfur species. Here, we report a mild-temperature, ambient-pressure MOF-to-oxide restructuring strategy to synthesize an MOF-derived AgCu oxide heterojunction (M-ACOH) from a Cu-based metal-organic framework (Cu-MOF) for efficient gas-phase methyl mercaptan (CH₃SH) oxidation. Introducing Ag into Cu-MOF under alkaline conditions induces MOF-to-oxide restructuring to form a porous AgCu oxide heterojunction containing CuO, Ag₂O, and metallic Ag-related domains. This restructuring increases the specific surface area by 15-fold (825.9 m² g^-1​) compared to pristine Cu-MOF and generates defect-rich interfaces, together with broadened visible-light absorption (Eg = 2.2 eV). Under low-intensity white LED irradiation (15 mW cm^-2), the M-ACOH achieved 100% CH₃SH removal and a CO₂ yield of 99.7%, significantly outperforming pristine Cu-MOF and the physically mixed CuO@Ag₂O reference. Electron spin resonance and RhB-based radical scavenger tests indicate that M-ACOH effectively suppresses disulfide accumulation by promoting a multi-oxidation network (h⁺, •OH, •O2^-, and ¹O₂)-driven pathway, bypassing the inefficient hydroperoxyl (•OOH) route observed in Cu-MOF. Furthermore, in situ diffuse reflectance infrared Fourier transform spectroscopy supported a stepwise sequence of CH₃SH adsorption/surface coupling, partial oxidation, and deep oxidation toward CO₂ and oxidized sulfur species. Post-reaction sulfur analyses via ion chromatography and XPS further revealed the formation of sulfate/oxidized sulfur species, supporting the deep oxidative conversion over M-ACOH. This work provides a mild MOF-to-oxide restructuring approach to design sulfur-affinitive, visible-light-active photocatalysts for low-energy indoor air purification.