Anion exchange membrane (AEM) water electrolysis (AEMWE) is considered an economical technology for producing green hydrogen energy. However, conventional AEMs comprising polymer backbones with anisotropically aligned cationic pendant groups exhibit unsatisfactory AEMWE performance and durability, limiting their practical implementation. Herein, a facile method for fabricating a durable high-performance AEM via a one-pot monomer-level Menshutkin (m-Men) reaction in a porous mechanical support is proposed. The rationally designed m-Men reaction between multifunctional alkyl halide and tertiary amine monomers creates a highly crosslinked polymer network with isotropically interconnected, high-density cationic groups. This unique structure is favorable for expediting anion conduction within the membrane and enhancing thermochemical robustness. The resultant membrane exhibits unprecedentedly high AEMWE performance with both non-platinum-group metal (PGM) and full-PGM electrodes at 5 wt.% potassium hydroxide and 80 °C, outperforming commercial state-of-the-art AEMs, with ensuring long-term operation. The proposed strategy provides a breakthrough approach for fabricating advanced membranes for various energy applications.