Endowing the implanted biomaterial with a wide range of functions, such as lubrication and antibacterial and anticoagulation properties, is essential for their safe clinical use. In the present study, based on the superlubrication mechanism of articular cartilage, a branched polyelectrolyte polymer (PEI-PMPC) was successfully synthesized based on tert-butyl hydroperoxide-initiated grafting polymerization and then applied to the biocompatible polyurethane (PU) surface. Specifically, the PU sheet was pretreated by polydopamine (PDA), and the PEI-PMPC polymer was grafted onto the PDA-modified PU surface by Schiff base reaction to generate a solid PDA/PEI-PMPC coating. The unmodified and modified surfaces were characterized by Fourier transform infrared spectroscopy, water contact angle, X-ray photoelectron spectroscopy, and surface zeta potential. To compare the lubrication, antibacterial behavior, and hemocompatibility, the relevant properties of the modified surfaces were evaluated by the tribological test, plate count method, surface morphology, hemolysis rate, activated partial thromboplastin time, and thrombin time. The experimental results demonstrated that the adhesion of bovine serum albumin, Escherichia coli, Staphylococcus aureus, platelets, and red blood cells was significantly decreased on the PEI-PMPC-modified PU surface compared with that of the unmodified PU surface. The multi-functional properties of the coating were attributed to the hydration layer formed by zwitterionic phosphorylcholine groups, and additionally, the cationic PEI served to kill the bacteria adhering to the surface. In summary, the bioinspired coating proposed in this study could potentially be used as a promising surface functionalization strategy for biomedical implants.