<p>This study explores the biocompatibility and inhibitory effects of magnesium (Mg) and its alloy, specifically the Mg–Cu alloy, on hepatocellular carcinoma (HCC) cells. The importance of this research stems from the potential use of magnesium alloys as biomaterials in bone repair and tissue engineering, while their effects on cancer cells have not been thoroughly investigated. Existing literature shows that although the degradation properties and biocompatibility of magnesium alloys have been examined, their anticancer properties remain a topic of debate. Thus, this study aims to clarify the impact of the Mg–Cu alloy on HCC cells, providing a theoretical foundation for its use in tumor therapy. We utilized various methods, including sample preparation, cell culture, cell viability assays (CCK8), cell cycle and apoptosis analysis, and luciferase activity detection, to comprehensively evaluate the effects of magnesium and its alloys on cellular behavior. Our findings indicate that the Mg–Cu alloy significantly reduces the viability of HCC cells–Huh7 and enhances apoptosis, with a pronounced effect noted at higher extract concentrations. Additionally, the Mg–Cu alloy effectively inhibits hepatitis B virus (HBV) replication, suggesting its potential as an antiviral agent. In summary, this study highlights the promising anticancer and antiviral properties of the Mg–Cu alloy, indicating its potential applications in biomedical fields. Future research should concentrate on the clinical implications and the mechanisms that underlie these effects.</p>