Inspired by the composite structure of natural joints, the soft-hard integrated layered artificial joint materials, synergistically combining the exceptional lubricity of hydrogel top layers with the superior load-bearing capacity of rigid alloy-based substrates, are emerging as a category of promising joint replacement material. Although many adhesion strategies have been developed to anchor the hydrogel upon alloy-based substrate, current interfacial adhesion strength lacks the performance levels to guarantee the integrity of composite structure when applied under practical service conditions. Here, we report an example of cation-anion interaction-induced transition layer to achieve secure bonding between the hydrogel and the hard substrate of titanium alloy, and have demonstrated its feasibility for the usage as artificial joint material. By leveraging the transition layer, we have prepared an integrated Ti6Al4V/Hydrogel artificial joint material, and tested the bonding strength through 90° peeling tests, shear peeling tests, and normal peeling tests. The results show that the hydrogel layer and the titanium alloy (i.e., Ti6Al4V) substrate have an ultra-high interfacial toughness (4000 J/m 2), with the normal bonding strength reaching 1.1 MPa and the shear strength reaching 1.44 MPa. In addition, under conditions of simulated human motion, the hydrogel maintains a low friction coefficient and retains excellent interfacial bonding properties over 5000 cycles. This work provides an effective strategy for fabricating soft-hard integrated artificial joints with tough interfacial bonding strength and low friction, benefitting the future coating design for alloy-based and other metallic composite materials with customized interfacial and surface properties toward various biomedical applications.