Benzimidazoles　are　a　versatile　class　of　scaffolds　with　important　biological　activities,　whereas　their　synthesis　in　a　lower-cost　and　more　efficient　manner　remains　a　challenge.　Here,　we　demonstrate　a　conceptually　new　radical　route　for　the　high-performance　photoredox　coupling　of　alcohols　and　diamines　to　synthesize　benzimidazoles　along　with　stoichiometric　hydrogen　(H2)　over　Pd-decorated　ultrathin　ZnO　nanosheets　(Pd/ZnO　NSs).　The　mechanistic　study　reveals　the　unique　advantage　of　ZnO　NSs　over　other　supports　and　particularly　that　the　features　of　Pd　nanoparticles　in　facilitating　the　cleavage　of　the　α-C−H　bond　of　alcohols　and　adsorbing　subsequently-generated　C-centered　radicals　hold　the　key　to　turning　on　the　reaction.　This　work　highlights　a　new　insight　into　radical-induced　efficient　benzimidazole　synthesis　pairing　with　H2　evolution　by　rationally　designing　semiconductor-based　photoredox　systems.　©　2023　Wiley-VCH　GmbH.