Display omitted •BiOCl/Bi2O3 coated mesh with superwetting was synthesized via a facile method.•This mesh demonstrates excellent oil/water separation and photocatalytic performance.•This mesh also possessed anti-biofouling and outstanding mechanical stability.•A double-layer mesh integrated oil separation and water purification in one device.•The versatile coated mesh has application prospect in complex oily sewage purification. A superhydrophilic/underwater superoleophobic BiOCl/Bi2O3 coated mesh was successfully prepared through a facile one-step hydrothermal method, which exhibits outstanding mechanical stability against sandpaper friction and resistance to water erosion and corrosive liquids. Notably, it demonstrates excellent oil/water separation efficiency and photocatalytic performance under visible light irradiation while preventing the adhesion of microorganisms to the coating surface, endowing anti-biofouling properties to the mesh. To achieve simultaneous separation of oil from water as well as degradation of soluble dye and bacteria pollutants in a single device, a superhydrophobic/superoleophilic BiOCl/Bi2O3 coated mesh was also prepared using surface modification with octadecanethiol. Subsequently, a dual-layer mesh (DLM) was obtained by overlaying the superhydrophilic BiOCl/Bi2O3 coating onto the superhydrophobic BiOCl/Bi2O3 coating. The resulting dual-layer mesh with its superwetting properties enables concurrent oil–water separation, photodegradation of organic contaminants and photocatalytic bactericidal activity within trapped sewage. Furthermore, this versatile BiOCl/Bi2O3 coated mesh can serve as a template for fabricating other bismuth-containing micro/nanostructure coatings with remarkable wetting properties. It is anticipated that such a versatile BiOCl/Bi2O3 coated mesh possessing superior superwetting properties, robust mechanical durability, excellent anti-biofouling properties and outstanding photocatalytic activity will find promising applications in complex oily sewage purification systems.