Making Li metal batteries (LMBs) with thinner Li is necessary to improve the cell energy density in practice. Li metal powders (LMPs) are beneficial for the facile manufacturing of thin Li, flexible cell design, and the 3D control of Li plating/stripping. However, the inhomogeneous surfaces of commercial LMPs limit their practical use in LMBs. Herein, a 20 µm-thick, LiNO3 preplanted LMP (LN-LMP) composite electrode, rationally designed for LMP surface stabilization, is presented. The addition of LiNO3 into the slurry uniformly modified the LMP surface by N-rich solid-electrolyte interphase (SEI). Preplanted LiNO3 further acts as a reservoir for the sustainable release into the electrolyte, thereby repairing the SEI upon cycling. The LMBs with LN-LMP exhibited excellent cycling performances (450 cycles at 87.3% retention) compared to the control cells, and even outperformed the cells with LiNO3-containing electrolytes. Further verification with high loading of a LiNixMnyCo1–x–yO2 (NMC) cathode demonstrated the feasibility of the practical cells and the versatility of the thin, LN-LMP anode combined with advanced electrolytes.