Low-temperature crystalline deposition techniques are important, especially for coating polymer films that cannot tolerate high temperatures. In this work, crystalline anatase titanium dioxide (TiO2) thin films were deposited by reactive radio-frequency (RF) magnetron sputtering on unheated poly(ethylene terephthalate) (PET) films. The stability of the polymer film under UV-light irradiation in air was then studied. With only a TiO2 layer the polymer film was degraded by in-air, UV radiation. However, a transparent bilayer coating, consisting of a TiO2 layer on top of an ultra-thin sputtered alumina (Al2O3) layer, on the PET film effectively protected the polymer layer from photo-oxidation. Furthermore, the top anatase TiO2 layer has very good photo-catalytic activity, as shown by its ability to photo-degrade rhodamine B dye solution. The combination of these two properties allows photo-stable and transparent polymer/ceramic layered media with a self-cleaning surface.