Vertically well-aligned zinc oxide (ZnO) nanorods were successfully grown by using wet chemical bath deposition synthesis on a seed-layer ZnO/polyethylene naphthalate at a low temperature. The strong and sharp (002) peak in the XRD indicated that ZnO nanorods grew vertically in the (002) direction along the z-axis on the substrate and had a high-quality single crystalline structure. The low value of the compressive strain (−0.0153%) revealed that ZnO nanorods preferred to grow along the c-axis. Hexagonal ZnO nanorods with diameters ranging from 10nm to 40nm grew vertically from the substrate and caused the sharp and strong peak in the UV range located at 390nm in the photoluminescence emission spectrum. These ZnO nanorods can be widely used for the development of flexible, optoelectronic, and elastic electronic devices.