High-performance separators characterized by excellent thermal stability, electrolyte wettability, porosity, and Li+ selectivity are vital for the safety and energy density of LiSBs, especially for suppressing polysulfide (LiPS) shuttling, which compromises the capacity and cycling stability. This study presents a novel separator design that combines template sacrificial and in situ growth methods to prepare a cobalt-imidazole framework-modified poly(ether ether ketone) inverse opal structure (ZIF-IO) that effectively inhibit the LiPS shuttle effect. The ZIF-IO separator, which has abundant electroactive sites, such as negative imidazole sites, enhances Li+ mobility. Co2+ attracts Sx2-, aiding LiPS adsorption and decomposition, thereby reducing LiPS shuttle diffusion. Through the ZIF-IO separator, the synergy of the Lewis acid–base effect and physical inhibition markedly curtailed LiPS transfer and lithium dendrite formation in the LiSB.