Polarization problem caused by the incomplete wetting of sodium on β″-alumina has been considered as one of the most difficult issues in Na-beta batteries. Here, nickel nanowire network coatings have been designed and fabricated directly on the β″-alumina electrolyte surface to effectively alleviate this problem. The coating consists of interconnecting nickel nanowires with diameter of about ∼100 nm, forming a highly porous morphology. The structural parameters of the nickel network coatings can be tuned mainly by the amount of the poly(methyl-methacrylate) soft template in the precursors. The nickel nanowire network coatings are demonstrated to greatly improve the wettability of the β″-alumina ceramics by molten sodium. Moreover, the nickel coating displays low sheet resistance of ca. 1 Ω sq−1. The results of Na/β″-alumina/Na symmetric cells at 350 °C reveal that the polarization and the interfacial resistance of the cell is alleviated intensively by the nickel coating, mainly due to the greatly improved wetting performance of the β″-alumina ceramics. This modification design and the soft-template-assisted synthetic method could be readily extended to any other substrate surfaces with arbitrary shape.