The metallic Na has been regarded as the most promising anode for next-generation sodium metal batteries (SMBs) owing to its high theoretical specific capacity, low redox potential, and low cost. The practical applications of Na metal, however, have still been severely hindered by the uncontrolled sodium dendrites growth during Na deposition and stripping processes, which leads to low Coulombic efficiency and poor cycling stability. In this study, sub-nano zinc oxide (ZnO) uniformly dispersed in three-dimensional (3D) porous nitrogen-doped (N-doped) carbon nanocube (ZnO@NC) was acquired as a stable host for dendrite-free Na metal anode. Benefiting from the in-situ electrochemically formed sodiophilic nucleation site (NaZn₁₃ alloy) and the enriched pore structure, rapid and uniform sodium deposition behavior can be performed. As expected, the ZnO@NC electrode delivers impressive electrochemical performance, an ultra-high areal capacity of 20 mAh·cm⁻² in the half-cell can be maintained for 2,000 h. In the symmetrical-cell, it can also exhibit up to 3,000 h at 3 mA·cm⁻² and 3 mAh·cm⁻² with low polarization potential. Furthermore, in the full-cell that matches with Prussian blue (PB) cathode, the Na@ZnO@NC anode performs the outstanding long-cycling and rate performance. Therefore, this work provides an effective strategy to inhibit the growth of Na dendrites for the development of high-safety and long-cycling SMBs.