In order to enhance the sluggish kinetics and suppress the polysulfide shuttle effect in high-loading lithium–sulfur (Li–S) batteries, it is crucial to design and synthesize catalysts exhibiting both high conversion rate and strong anchoring effect toward polysulfide species. Herein, based on theoretical predictions, spent cathode materials (LiCoO₂ and LiMn₂O₄) from spent lithium-ion batteries are converted into a bifunctional catalyst (Co─MnO) for Li–S batteries through the high-temperature shock method. Owing to the synergistic catalytic and anchoring effect of polysulfide species exhibit by Co─MnO, superior electrochemical performance, including excellent rate performance (707 mAh g⁻¹ at 4C) and high stability (capacity fading of 0.058% per cycle over 400 cycles at 1C) can be delivered under a low areal catalyst loading (<0.5 wt%). This work not only offers a new design strategy for Li–S catalysts, but also proposes a promising approach to transform spent LIBs into highly efficient catalysts.