In the pursuit of high‐energy‐density lithium metal batteries (LMBs), the development of stable solid electrolyte interphase (SEI) is critical to address issues such as lithium dendrite growth and low Coulombic efficiency. Herein, we propose a facile strategy for the in‐situ fabrication of a LiCl‐rich artificial SEI layer on Li surfaces through reaction of MoCl5 with Li (Li@MoCl5). The resulting artificial SEI significantly enhances the uniformity of Li deposition, effectively suppresses dendrite formation, and improves electrochemical performance. As a result, Li@MoCl5 symmetric cells demonstrate remarkable stability, achieving continuous cycling of 4200 h under a high current density of 10 mA cm–2 with an areal capacity of 1 mAh cm–2. Full‐cells employing Li@MoCl5 exhibit superior cycling stability and rate capability, even at high cathode loading (17 mg cm–2). These results highlight the potential of this interface engineering strategy for advanced practical application of LMBs.