Zinc oxide (ZnO) nanoparticles and nanoparticles of luminescent zinc oxide (ZnO:Zn) phosphor were successfully synthesised and well characterised. A transparent polystyrene composite sheet containing ZnO:Zn nanoparticles was prepared by a solvent casting method. The sheet manifested comparable transmission to a virgin polystyrene film due to very uniform dispersion of the ZnO:Zn nanoparticles into the polystyrene. Evidence for uniform dispersion was evident in both its luminescent properties and in a SEM image. The photoluminescent characteristics of the ZnO:Zn, both as a pure powder and embedded in a polystyrene matrix, are reported. The uniformity of the photoluminescence of the composite sheet under near ultraviolet excitation is demonstrated. The luminescent ZnO:Zn nanoparticles are shown to have applications for use not only as an inhibitor of the ultraviolet degradation of polymers, but also for providing polymers with light emitting functionality.