Additively manufactured biodegradable metals demonstrate great potential in orthopedic implants, enabling patient-specific designs and eliminating the need for secondary surgeries through degradation. Zinc (Zn)-magnesium (Mg) alloys reconcile the dilemma between Zn's low biological activity and Mg's rapid degradation, and become promising bone-repair materials. However, Zn-Mg alloys currently fabricated via additive manufacturing exhibit high strength but low ductility, and the effects and mechanisms by which Mg influences their degradation and bone regeneration remain unclear and debated. Here, Zn-xMg alloys (x = 0, 0.1, 0.2, 0.4, 1.0 wt%) are prepared using laser powder bed fusion (L-PBF). Adding Mg refines the microstructure and forms brittle secondary phases, improving strength but reducing ductility. Zn-0.4Mg shows superior balance, with an ultimate tensile strength of 289.40 MPa and elongation of 12.53%. The addition of Mg slows degradation by forming protective Mg-containing products and accelerating the passivation. Furthermore, Mg alloying significantly enhances bone regeneration, as indicated by both in vitro and in vivo tests. This improvement is driven by the release of less Zn