AbstractThe employment of ultrathin Li metal electrodes with matched capacity with current cathodes and improved electrochemical stripping/plating behaviors plays a key role in the realization of high‐energy‐density batteries. However, their fabrication remains challenging using regular cold rolling processing due to inferior processibility of metallic Li. Herein, a facile molten metal doctor‐blade casting approach is explored to fabricate uniform metallic Li layers with thickness ranging from 10 to 50 µm on regular battery Cu current collectors with a lithiophilic Sn interphase layer. The enhanced surface wettability between Li and the spontaneously formed Li–Sn alloy helps to realize uniform spreading, and formation of an ultrathin and uniform metallic Li layer. The existence of the Li–Sn alloy in the bulk of metallic Li electrode helps to reduce the nucleation barrier and improve the electrochemical performance of the Li metal. With a cathode areal capacity of 2.8 mA h cm⁻² the LiCoO₂||Li/Li–Sn full cell shows improved capacity retention from 58% to 77% after 100 cycles at a lower Negative/Positive ratio of 2/1, offering a high energy density of 662.4 W h kg⁻¹. The enhanced electrochemical performance of the as‐fabricated ultrathin Li metal electrode with high energy density opens up a promising pathway for realizing next‐generation high‐energy‐density batteries.