The　photoresponse　and　photocatalytic　efficiency　of　bismuth　oxychloride　(BiOCl)　are　greatly　limited　by　rapid　recombination　of　photogenerated　carriers.　The　construction　of　porous　single-crystal　BiOCl　photocatalyst　can　effectively　alleviate　this　issue　and　provide　accessible　active　sites.　Herein,　a　facile　chelated　ion-exchange　strategy　is　developed　to　synthesize　BiOCl　mesoporous　single-crystalline　nanosheets　(BiOCl　MSCN)　using　acetic　acid　and　ammonia　solution　respectively　as　chelating　agent　and　ionization　promoter.　The　strong　chelation　between　acetate　ions　and　Bi3+　ions　introduces　acetate　ions　into　the　precipitated　product　to　exchange　with　Cl-　ions,　resulting　in　large　lattice　mismatch,　strain　release,　and　formation　of　void-like　mesopores.　The　prepared　BiOCl　MSCN　photocatalyst　exhibits　excellent　catalytic　performance　with　99%　conversion　and　98%　selectivity　for　oxidation　of　benzyl　alcohol　to　benzaldehyde　and　superior　general　adaptability　for　various　aromatic　alcohols.　The　theoretical　calculations　and　characterizations　confirm　that　the　superior　performance　is　mainly　attributed　to　the　abundant　oxygen　vacancies,　plenty　of　accessible　adsorption/active　sites　and　fast　charge　transport　path　without　grain　boundaries.　©　2023　Wiley-VCH　GmbH.