Photocatalytic elimination of the toxic chemicals in water effluents is of interest as a green approach and surface area of the catalyst material is critical for high performance. Atomic layer deposition (ALD) provides a promising route to immobilize conformal thin film photocatalysts on the rough and high surface area substrates. In this study, very thin 10 nm of ZnO films were deposited on glass fabric substrate, and their photocatalytic activities were determined with and without post-processing annealing. After four hours of the solar simulator and UV lamp illuminations, the solutions with ZnO ALD films showed up to 97% degradation of the methylene blue in, faster than the films on planar substrates reported in the literature. With our proposed approach, a model contaminant is successfully cleaned quickly without the need to remove photocatalyst materials afterward. Reaction kinetics showed a first-order reaction for the photodegradation of the methylene blue in the presence of ZnO photocatalyst thin films. Structural and optical characterizations also showed that the defects play a significant role in the higher photocatalytic performance of the films explained by XRD, XPS, UV-Vis, and PL spectroscopy results.