The shuttle effect and sluggish conversion kinetics of lithium polysulfides (LiPS) hamper the practical application of lithium���sulfur batteries (LSBs). Toward overcoming these limitations, herein an in situ grown C2N@NbSe2 heterostructure is presented with remarkable specific surface area, as a Li���S catalyst and LiPS absorber. Density functional theory (DFT) calculations and experimental results comprehensively demonstrate that C2N@NbSe2 is characterized by a suitable electronic structure and charge rearrangement that strongly accelerates the LiPS electrocatalytic conversion. In addition, heterostructured C2N@NbSe2 strongly interacts with LiPS species, confining them at the cathode. As a result, LSBs cathodes based on C2N@NbSe2/S exhibit a high initial capacity of 1545 mAh g���1 at 0.1 C. Even more excitingly, C2N@NbSe2/S cathodes are characterized by impressive cycling stability with only 0.012% capacity decay per cycle after 2000 cycles at 3 C. Even at a sulfur loading of 5.6��mg cm���2, a high areal capacity of 5.65 mAh cm���2 is delivered. These results demonstrate that C2N@NbSe2 heterostructures can act as multifunctional polysulfide mediators to chemically adsorb LiPS, accelerate Li-ion diffusion, chemically catalyze LiPS conversion, and lower the energy barrier for Li2S precipitation/decomposition, realizing the ���adsorption-diffusion-conversion��� of polysulfides.