Sn-based halide perovskites are expected to solve the problems of the shuttle effect and sluggish redox kinetics of lithium polysulfides (LiPSs) in lithium–sulfur batteries (LSBs) due to their high conductivity and electrocatalytic activity, but their intrinsic catalytic mechanism for LiPSs remains to be explored. Herein, halide perovskites with varying halide anions, Cs₂SnX₆ (X = Cl, Br, I), are purposefully designed to unveil the halogen-induced regulatory mechanism. Theoretical calculations demonstrate that increasing the halogen atomic number induces the shift of the p-band center closer to the Fermi level, which results in the localized charge distribution around halide anions and rapid charge separation/transfer at Sn sites, enhancing the adsorptive and catalytic activity and redox kinetics of LiPSs. Experimental investigations exhibit that LSBs assembled with the Cs₂SnI₆ modified separator deliver a high initial capacity of 1000 mA h g⁻¹ at 2C, with a minimum decay rate of 0.068% per cycle after 500 cycles. More impressively, the Cs₂SnI₆ battery with a high sulfur loading (6.1 mg cm⁻²) and a low electrolyte/sulfur ratio (5.5 μL mg⁻¹) achieves a remarkable reversible capacity of 768.8 mA h g⁻¹, along with robust wide-temperature-tolerant cycling performance from −20 to 50 °C. These findings underscore the critical role of p-band center regulation in rationally designing advanced LSBs.