Zinc oxide (ZnO) nanostructures are among the most interesting nanomaterials due to their remarkable performance in optics, electronics, semiconducting materials, and photocatalysis. Recent literature reports the synthesis and characterization of ZnO-polymer nanocomposites which are more flexible materials for various applications. This paper is concerned with the synthesis of cellulose acetate butyrate (CAB) nanofiber mats useful as substrates for growing ZnO nanocrystals. CAB nanofibers and CAB nanofibers containing zinc acetate as precursor for ZnO nanoparticles are prepared via electrospinning from adequate solvents: 2-methoxyethanol and 2-methoxyethanol-DMF-water mixture, respectively. Formation and growing of ZnO nanocrystals are performed using a chemical deposition technique that implies multiple alternative dipping in an ammonium zincate bath and hot water bath, respectively. The morphology of CAB nanofibers and CAB-ZnO nanocomposites is studied by scanning electron microscopy (SEM). The presence of ZnO nanocrystals is evidenced by X-ray diagrams and FTIR analysis. The potential of the obtained composites as photocatalysts for dye degradation is investigated over two organic pollutants: Rhodamine B and methylene blue, in visible light, and the results of UV-vis analysis are reported.