This study explores the corrosion behavior of a novel hydroxyapatite (HA) nanostructure coating, which combines the benefits of HA, collagen, and whey protein, on the surface of etched AZ31 magnesium alloy. The HA coating was synthesized through electrochemical deposition, while collagen and whey protein were added through a dip coating method. The corrosion behavior of the coated alloy was evaluated using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization tests. The results indicate that the HA coating significantly enhances the corrosion resistance of the AZ31 alloy, characterized by a notable reduction in corrosion current density and an increase in charge transfer resistance. The synergistic effect of collagen and whey protein in the HA coating is found to improve corrosion protection, likely due to the formation of a stable and compact film on the alloy surface. This study highlights the potential of this novel HA coating for biomedical applications, particularly in the development of biodegradable implants and medical devices. This combination enhances both corrosion resistance and biocompatibility, highlighting the potential of these coatings for magnesium-based biomedical implants.