Lithium metal has been considered the ultimate anode material in Li rechargeable batteries because of its exceptionally high theoretical specific capacity (3860 mAh g⁻¹) and extremely low redox potential (−3.04 V vs. standard hydrogen electrode). However, the uncontrollable formation of dendritic Li during Li plating/stripping cycling processes generates electrochemically disconnected Li chunks from the electrode, which consumes an active Li source in the electrolyte, thus degrading the electrolyte and leading to low Coulombic efficiency and safety concerns in Li rechargeable batteries. Therefore, the development of stable Li-metal anodes (LMAs) is required for highly reversible Li plating/stripping on the anode side. In this regard, magnesium metal and Mg-based alloys have attracted considerable attention as new LMAs because of their good compatibility with Li and high lithiophilicity. In this review, we introduce the recent advances and strategies for Mg-metal- and Mg-based alloy materials to achieve high durability in next-generation Li-ion batteries and all-solid-state batteries. In addition, we discuss the challenges in the development of Mg-based alloys and their future perspectives. The comprehensive understanding of Mg-metal- and Mg-based alloy materials for LMAs in this review will offer the reader the inspiration to establish an effective strategy for future research.