A UV-curable polyether-modified polysiloxane polyurethane acrylate prepolymer PESiUA that can be used for polyvinyl chloride leather finishing agents has been synthesized and characterized by nuclear magnetic resonance, Fourier transform infrared spectroscopy, and gel permeation chromatography. The prepolymer exhibited excellent compatibility with acrylate monomers, satisfying photopolymerization efficiency and good yellowing resistance. The influences of the monomers on the properties of the UV-cured film were systematically studied. The results showed that the increase in the functionality of monomers can increase the thermostability, glass transition temperature, tensile strength, tensile modulus, dispersion surface energy, and decrease the contact angle and elongation at break. More significantly, the PVC leather finishing agent designed based on the photopolymerizable polyether-modified polysiloxane polyurethane acrylate prepolymer PESiUA possessed excellent performances and had great application potential, due to the combination of advantages of polysiloxane segment and polypropylene glycol segment as well as photopolymerization technique.