Herein, ZnS nanoparticles on Nitrogen (N) and Sulphur (S) co-doped carbon nanosheets (ZnS@NSC) are prepared through a highly efficient sol-gel synthesis. Interestingly, the ZnS nanoparticles are encapsulated in ultrathin carbon shells, which are crucial to buffer the volume changes of ZnS during sodium ion intercalation/de-intercalation. Meanwhile, the nanosheets and ultrafine carbon shells together constitute the N, S co-doped carbon framework, which not only can give rise to abundant active sites for sodium storage but also greatly enhance the electrical conductivity. As a result, the ZnS@NSC achieves a reversible capacity of 734 mAh g−1 at 0.5 A g−1 and excellent cycling stability (73.6% capacity retention after 380 cycles at 0.5 A g−1).