Ultraviolet weathering performance of polyvinyl chloride (PVC) filled with different concentrations of wood flour was studied. Extruded PVC/wood-flour composite samples were subjected to cyclic ultraviolet lamps/condensation exposures and assessed over a total of 400 and 2600 hours. Each assessment consisted of DRIFT-FTIR and XPS collections, contact angle measurement, color measurement, and tensile property testing. The experimental results indicated that wood flours are effective chromophore materials since their incorporation into a rigid PVC matrix accelerated the degradation of the polymeric matrix. Photodegradation converted unfilled PVC samples to a colored material of lower extensibility. Although composite samples exhibited greater discoloration than unfilled PVC samples, they retained all their original strength and stiffness properties even after 2600 hours of cyclic UV irradiation/condensation exposures.