Polyelectrolyte-grafted ultra-high-molecular-weight polyethylene (UHMWPE) has been proven efficient in friction and wear reduction. However, owing to the damaged molecular structure and material stability, the modified material experiences compromised mechanical and tribological properties under immersed, aqueous working environment. To achieve enhanced material strength and water resistance, carbon nanotubes (CNTs) were modified and used as reinforcing agent. Nanoindentation tests and macroscopic reciprocating friction tests have shown significant improvements in mechanical and tribological properties: friction coefficient and wear rate down to 0.0086 and 5.6 × 10-8 mm3(Nm)- under saline-lubricated conditions, which maintained relatively stable during 120-day saline pre-soaking. This combination of strong hydration lubrication and superior material strength offers a promising design of superlubricating artificial cartilage with high wear resistance and long lifetime.