A novel family of biodegradable pseudo-protein biomaterials, arginine (Arg)-based poly(ester urea urethane) (Arg-PEUU), were synthesized and applied as a better protective and bio-functional coating for bio-absorbable magnesium alloy MgZnYNd as a stent model. The Arg-PEUU coatings were stronger than poly(glycolide-co-lactide) (PLGA) coating with 11.9-103.4% higher critical lateral force. Electrochemical tests and in vitro immersion results demonstrated that the Arg-PEUU-coated MgZnYNd alloys have a significantly better corrosion resistance. The Arg-PEUU coating also showed reduced platelet adhesion and hemolysis rate in acute blood contact testing. Immunofluorescent actin and vinculin stainings showed that the Arg-PEUU coating had a far better cell adhesion of human umbilical vein endothelial cells (HUVEC), and also showed no cytotoxicity toward both HUVEC and human aortic smooth muscle cells (HASMC). The Arg-PEUU coating stimulated HUVEC to release significantly higher amounts of nitric oxide (NO) than the controls, suggesting the Arg-PEUU coating has the ability to retard thrombus and restenosis. The superb corrosion retardation, hemocompatibility and cytocompatibility of the Arg-PEUU coating as well as its induced indigenous NO production biofunctionality indicate that the newly developed Arg-PEUU biodegradable copolymer family may have the potential to offer a far greater protection of magnesium-based implantable cardiovascular stents.