In the face of frequent oil spills and dye emissions, membrane technology is an efficient method to treat wastewater. However, selectivity, membrane fouling and high operating pressure are tricky problems for practical membrane applications. Hence, it is desirable to design a novel membrane with high selectivity, high flux and superior antifouling properties for gravity-driven separation of complex oily wastewater. In this study, bioinspired by sea urchins with good self-cleaning properties, an urchin-like Ni/Co layered double hydroxide (LDH) surface was grown onto stainless steel mesh (SSM) via a facile hydrothermal method. Due to the unique hierarchical architecture and surface chemistry, Ni/[email protected] displays a robust self-cleaning oil-repellent ability without hydration. Combining the unique superwettability and highly porous nanostructure, Ni/[email protected] could be used to separate various oil/water mixtures and emulsions efficiently under only gravity-driven conditions. In addition, Ni/[email protected] exhibits great catalytic degradation ability of dye solutions in a short time. Notably, Ni/[email protected] displays excellent physical, chemical and thermal stability in acidic, alkaline and saline environments. Consequently, Ni/[email protected] possesses broad application prospects with superior self-cleaning and outstanding catalytic degradation ability of aromatic dyes. It shows promising application value in practical complex oily wastewater treatment without complicated operations and chemicals.