<p>The effect of cooling rate on the microstructure, hardness, and corrosion behavior of Mg-2Zn and Mg-2Zn-1Mn alloys was investigated using a stepped permanent mold that provides three distinct solidification conditions. XRD analysis revealed the formation of MgZn, MgZn₂, and Mg₂Zn₃ intermetallic phases together with the α-Mg matrix. As the cooling rate increased from the thick (Step I) to the thin (Step III) section, the microstructure became finer and more dendritic, resulting in approximately a 20% increase in Vickers hardness during potentiodynamic polarization tests in 3.5 wt.% NaCl solution showed that corrosion behavior strongly depends on both alloy composition and cooling rate. In Step I, the Mg-2Zn-1Mn alloy exhibited a corrosion current density about five times higher than that of Mg-2Zn, whereas in Step III, this difference decreased to roughly three times. In Step II, the Mg-2Zn alloy displayed the lowest corrosion current density. Immersion corrosion tests confirmed that the Mg-2Zn alloy generally exhibited higher weight loss and corrosion rates than the Mg-2Zn-1Mn alloy; after 3 days, both alloys showed similar behavior in Step I, while the Mg-2Zn alloy exhibited approximately 40-50% higher corrosion rates in Steps II and III. These results demonstrate the combined influence of Mn alloying and cooling rate on microstructural refinement, hardness evolution, and corrosion performance of Mg-Zn-based alloys.</p>