Oxidizing CH4 into liquid products with O2 under mild conditions still mainly relies on metal catalysis. We prepared a series of sulfone‐modified conjugated organic polymers and found that the catalyst with proper SVI content (0.10) could drive O2→H2O2→⋅OH to oxidize CH4 into CH3OH and HCOOH directly and efficiently at room temperature under light irradiation. Experimental results showed that after 4 h reaction, decomposition rate and residual amounts of H2O2 were 81.21 % and 4.83 mmol gcat−1 respectively, and CH4 conversion rate was 22.81 %. Mechanism studies revealed that illumination could induce the homolytic dissociation of S=O bonds on catalyst to produce oxygen and sulfur radicals, where the ⋅O could adsorb and activate CH4, and the ⋅S could supply electrons for 1O2 to generate H2O2 and then for decomposing the H2O2 into ⋅OH timely to oxidize CH4. This research provided a novel organic catalysis approach for oxygen activation and utilization. In a process of methane conversion photocatalyzed by the sulfone‐decorated conjugated organic polymer, S‐CTTP, light irradiation first induced the homolytic dissociation of S=O bonds in sulfone groups on the catalyst surface to generate free radicals. The radicals drive efficient conversion of 1O2 to H2O2 and then ⋅OH, for selective oxidation of adsorbed CH4 into CH3OH and HCOOH.