Membrane　separation　techniques　could　address　global　water　scarcity　and　ensure　water　safety.　However,　the　unavoidable　concentration　polarization　effect　remains　a　formidable　challenge.　Here,　we　present　a　nanoconfined　catalysis　boron　nitride　membrane　confining　active　nanoparticles　to　elaborately　regulate　molecular　separation　and　pollutant　degradation.　For　positively　charged　pollutant,　the　nanoconfined　catalysis　membrane　demonstrates　a　water　permeance　reaching　high　up　to　1549　​L　​m−2　​h−1　​bar−1,　which　also　substantially　increases　the　removal　efficiency　of　organic　pollutants　from　71.9　​%　to　above　99.9　​%.　For　negatively　charged　pollutant,　the　membrane　achieves　nearly　100　​%　reduction　to　p-aminophenol　within　4.06　ms　retention　time　across　100　operational　cycles.　Density　functional　theory　calculation　results　further　confirm　the　charge　selection　of　nanoconfined　catalysis　boron　nitride　membranes　for　enhanced　water　decontamination.　The　superior　performance　of　nanoconfined　catalysis　membranes　arises　from　synergistically　integrating　stable　2D　nanochannels,　uniform　catalytic　layers,　and　controlled　charge　transfer,　effectively　mitigating　concentration　polarization　in　wastewater　treatment.　©　2025　The　Authors