The selective oxidation of methane under mild conditions remains the “Holy Grail of Catalysis”. The key to activating methane and inhibiting over-oxidation of target oxygenates lies in designing active centers. Copper nanoparticles were loaded onto TiO₂ nanofibers using the photo-deposition method. The resulting catalysts were found to effectively convert methane into C1 oxygenated products under mild conditions. Compared with previously reported catalysts, it delivers a superior performance of up to 2510.7 mmol·g_Cu⁻¹·h⁻¹ productivity with a selectivity of around 100% at 80 °C for 5 min. Microstructure characterizations and density functional theory (DFT) calculations indicate that TiO₂ in the mixed phase of anatase and rutile significantly increases the Cu⁺/Cu⁰ ratio of the supported Cu species, and this ratio is linearly related to the formation rate of oxygen-containing species. The Cu_I site promotes the generation of active O species from H₂O₂ dissociation on Cu₂O (111). These active O species reduce the energy barrier for breaking the C–H bond of CH₄, thus boosting the catalytic activity. The methane conversion mechanism was proposed as a methyl radical pathway to form CH₃OH and CH₃OOH, and then the generated CH₃OH is further oxidized to HOCH₂OOH.