Tribological characteristics of ultra-high molecular weight polyethylene (UHMWPE) composites with 10% short carbon fibres (SCF) lubricated in water with polyvinylpyrrolidone (PVP) as a modifier were investigated. The aqueous solutions with varying concentrations of PVP were prepared, and their viscosity-enhancing action, friction-reducing properties and anti-wear performances were studied under different loading conditions equivalent to 10 and 20 MPa of contact pressures at a constant sliding speed of 20 mm/s. The results showed that PVP is an excellent viscosity modifier for water. PVP-modified water exhibited excellent performance compared to distilled water, reducing the wear and friction coefficient of neat UHMWPE up to 25%. The anti-wear properties of UHMWPE-SCF composite were also improved with PVP modified water lubrication, yielding a maximum reduction of wear up to 45%. PVP seems to be a promising additive of modifying the lubricating properties of distilled water for water-based lubrication.