In this study, we demonstrated hydration lubricity improvement via the synergistic effects of free polymers and brush films formed on a surface. We analyzed the hydration interfacial structure using neutron reflectometry and measured the shear viscoelasticity of the film using the fiber wobbling method. The results revealed that the volume fraction of the free polymer adsorbed on the brush film increased, leading to an improvement in the load-carrying capacity. Additionally, a water-rich layer formed on the surface owing to the brush film’s exclusion-volume effect, and this layer reduced the shear resistance and increased the lubricity. These insights into the composite films of polymer brushes and adsorbed free polymers offer new perspectives and design principles for the development of hydration lubrication.