Separators serve as critical components in batteries, bearing the responsibility for battery safety. In addition to the demand for increased flame resistance of separators, there is a growing interest in the additional functions of battery separators. In this work, a multifunctional coating integration strategy is proposed for battery separators via the versatility of metal–organic frameworks. A versatile and high‐safety MIP‐202@2320 composite separator is engineered and it is integrated into lithium–sulfur batteries. The presence of Cl− and the porous structure of MIP‐202 impart flame‐retardant characteristics and high electrolyte retention (80%) to resulting separators. Moreover, coupled with the negatively charged electron cloud formed by Cl− ions within the channels, it can selectively impede the polysulfides from migrating toward the anode, while concurrently facilitating the movement of Li+ ions. The assembled lithium–sulfur battery with MIP‐202@2320 as the separator maintains an impressive 71.8% capacity retention even after 600 cycles at a 0.5C rate. This multifunctional integration strategy not only boosts the performance of lithium–sulfur batteries but also pioneers a new direction for the design of future battery separators for different kinds of batteries.