Lithium–sulfur (Li–S) batteries suffer from multiple complex and often interwoven issues, such as the low electronic conductivity of sulfur and Li₂S/Li₂S₂, shuttle effect, and sluggish electrochemical kinetics of lithium polysulfides (LiPSs). Guided by theoretical calculations, a multifunctional catalyst of isolated single-atom nickel in an optimal Ni–N₅ active moiety incorporated in hollow nitrogen-doped porous carbon (Ni–N₅/HNPC) is constructed and acts as an ideal host for a sulfur cathode. The host improved electrical conductivity, enhanced physical-chemical dual restricting capability toward LiPSs, and, more importantly, boosted the redox reaction kinetics by the Ni–N₅ active moiety. Therefore, the Ni–N₅/HNPC/S cathode exhibits superior rate performance, long-term cycling stability, and good areal capacity at high sulfur loading. This work highlights the important role of the coordination number of active centers in single-atom catalysts and provides a strategy to design a hollow nanoarchitecture with single-atom active sites for high-performance Li–S batteries.