Halogenated　methane　serves　as　a　universal　platform　molecule　for　building　high-value　chemicals.　Utilizing　sodium　chloride　solution　for　photocatalytic　methane　chlorination　presents　an　environmentally　friendly　method　for　methane　conversion.　However,　competing　reactions　in　gas-solid-liquid　systems　leads　to　low　efficiency　and　selectivity　in　photocatalytic　methane　chlorination.　Here,　an　in　situ　method　is　employed　to　fabricate　a　hydrophobic　layer　of　TaOx　species　on　the　surface　of　NaTaO3.　Through　in-situ　XPS　and　XANES　spectra　analysis,　it　is　determined　that　TaOx　is　a　coordination　unsaturated　species.　The　TaOx　species　transforms　the　surface　properties　from　the　inherent　hydrophilicity　of　NaTaO3　to　the　hydrophobicity　of　TaOx/NaTaO3,　which　enhances　the　accessibility　of　CH4　for　adsorption　and　activation,　and　thus　promotes　the　methane　chlorination　reaction　within　the　gas-liquid-solid　three-phase　system.　The　optimized　TaOx/NaTaO3　photocatalyst　has　a　good　durability　for　multiple　cycles　of　methane　chlorination　reactions,　yielding　CH3Cl　at　a　rate　of　233　µmol　g−1　h−1　with　a　selectivity　of　83%.　In　contrast,　pure　NaTaO3　exhibits　almost　no　activity　toward　CH3Cl　formation,　instead　catalyzing　the　over-oxidation　of　CH4　into　CO2.　Notably,　the　activity　of　the　optimized　TaOx/NaTaO3　photocatalyst　surpasses　that　of　reported　noble　metal　photocatalysts.　This　research　offers　an　effective　strategy　for　enhancing　the　selectivity　of　photocatalytic　methane　chlorination　using　inorganic　chlorine　ions.　©　2024　Wiley-VCH　GmbH.