This study focuses on the effects of precursor concentration on the structural and the optical properties of ZnO nanostructures electrodeposited on a metallic Sn seed layer. ZnO nanostructures were synthesized on Sn-coated quartz substrates by using various ZnCl2 concentrations and were compared with ZnO nanostructures grown on indium-tin-oxide (ITO) glass. The photoluminescence intensity ratio of the UV emission to the visible emission and the full width at half maximum values of the UV emission, as well as the morphologie of ZnO nanostructures grown on Sn seed layers, were controlled by using the ZnCl2 concentration. In addition, the structural and the optical properties of the ZnO nanostructures grown on Sn-coated quartz substrates were enhanced with a considerable improvement in the vertical orientation and uniformity compared with those of ZnO nanostructures grown on ITO glass. Based on these results, we proposed an effective method for the synthesis of high-quality ZnO nanostructures with vertically uniform orientations and high luminescence efficiency by using a metallic Sn seed layer.