Plasma-sprayed HA coatings on metallic implants are widely used for clinical applications. However, typical lamellar structure along with plasma-sprayed coatings usually leads to weak inter-splat adhesion and impair their mechanical properties. In this research, graphene nanosheet (GNS) reinforced HA coatings were fabricated using plasma spray; these GNSs retained their original structure and distributed homogeneously in the as-sprayed coatings. On the basis of instrumented microindentation tests with and without multiple partial unloading, as compared with the monolithic HA coating, the inter-splat friction force increased by ~ 8.7% for the 1.0 wt% GNS/HA coating, and it slightly decreased to ~ 6.5% for the 2.0 wt% GNS/ HA coating due to GNS agglomeration. Meanwhile, the added GNSs contributed greatly to the indentation yield strength of the HA coatings. These results illustrated that these embedded GNSs at splat boundaries are potential in splat-boundary strengthening and resisting splat sliding.