In this study, in view of the corrosion resistance and bio functionality limitations of medical magnesium alloys, a PCL/MAO@TiO₂ NPS composite coating was fabricated to enhance biodegradable magnesium alloy orthopedic implants. This composite coating effectively inhibited pitting corrosion and decreased the degradation rate of the magnesium alloy substrate. Specifically, the corrosion current density of the overall specimen decreased by five orders of magnitude compared to that of the substrate. In vitro cell experiments demonstrated that the composite coating significantly decelerated the degradation of the magnesium alloy. The degradation products and appropriate magnesium ion concentration promoted cell growth and proliferation. After 72-h co-culturing of specimen extracts with cells, cell viability remained at 100%. Antimicrobial test results showed that due to the synergistic effect of ultraviolet treated TiO₂ nanoparticles and other components, the specimens exhibited excellent antimicrobial properties. Moreover, in vivo animal implantation tests revealed that the PCL/MAO@TiO₂ NPS composite coated specimens had remarkable bone enhancing capabilities, which were conducive to the healing and functional restoration of bone tissue. Overall, the numerous advantages suggest that the PCL/MAO@TiO₂ NPS composite coatings hold great promise for improving magnesium alloy implants in clinical applications.