This review discusses the development and application of corrosion-resistant plasma electrolytic oxidation (PEO) coatings on magnesium (Mg) alloys. Mg alloys are lightweight and have excellent mechanical properties, but their high chemical reactivity leads to poor corrosion resistance, especially in marine environments. PEO is an eco-friendly and cost-effective technology that forms a dense oxide layer on Mg alloys, improving their corrosion resistance. The review summarizes the growth mechanisms and corrosion processes of PEO coatings on Mg alloys, highlighting two main approaches to enhance corrosion resistance: improving the internal structure of the coating and optimizing its phase composition. Key strategies include optimizing coating thickness, roughness, and density; repairing micropores and cracks; and introducing corrosion-resistant compounds through doping. Micropores and cracks are identified as critical points for corrosion, and sealing these defects is an effective strategy. Modifying the phase composition of the coating can minimize corrosion and significantly enhance the corrosion resistance of Mg alloys. The review also discusses future challenges and potential advancements in PEO coatings for Mg alloys, including the need to improve the theoretical understanding of PEO mechanisms, optimize electrolyte and electrical parameters, develop efficient power supply systems, and enhance the corrosion resistance of coatings through the use of insoluble metal salts. The study emphasizes the importance of further research to address existing limitations and improve the performance of PEO coatings on Mg alloys.This review discusses the development and application of corrosion-resistant plasma electrolytic oxidation (PEO) coatings on magnesium (Mg) alloys. Mg alloys are lightweight and have excellent mechanical properties, but their high chemical reactivity leads to poor corrosion resistance, especially in marine environments. PEO is an eco-friendly and cost-effective technology that forms a dense oxide layer on Mg alloys, improving their corrosion resistance. The review summarizes the growth mechanisms and corrosion processes of PEO coatings on Mg alloys, highlighting two main approaches to enhance corrosion resistance: improving the internal structure of the coating and optimizing its phase composition. Key strategies include optimizing coating thickness, roughness, and density; repairing micropores and cracks; and introducing corrosion-resistant compounds through doping. Micropores and cracks are identified as critical points for corrosion, and sealing these defects is an effective strategy. Modifying the phase composition of the coating can minimize corrosion and significantly enhance the corrosion resistance of Mg alloys. The review also discusses future challenges and potential advancements in PEO coatings for Mg alloys, including the need to improve the theoretical understanding of PEO mechanisms, optimize electrolyte and electrical parameters, develop efficient power supply systems, and enhance the corrosion resistance of coatings through the use of insoluble metal salts. The study emphasizes the importance of further research to address existing limitations and improve the performance of PEO coatings on Mg alloys.