Zinc oxide (ZnO) is considered a highly promising photovoltaic material due to its low resistivity and high transmittance properties. Modifying the surface chemical properties of semiconductors by doping chemicals is an effective method of enhancing their performance. Recently, a piezoelectric nanogenerator (PENG) has been used for sustainable energy production as a promising solution. To improve the output performance of PENG, we doped ZnO nanorod arrays with chlorine in this study. To grow low-density chlorine-doped ZnO nanorod structures on indium tin oxide glass without a seed layer, we employed a hydrothermal method. These structures were then used to fabricate nanogenerators. The differences between substrates with and without seed layers were compared in terms of nanorod growth and the impact of doping the nanorods. After sputtering a layer of platinum (Pt) film onto the ZnO nanorod arrays, nanogenerators were assembled to have sputtered and nonsputtered nanostructures at the same time. These chlorine-dopped nanogenerators were driven by ultrasound to measure the optimal current–voltage (I–V) characteristics, and the results showed a current of 5.62 × 10−6 A and a voltage of 4.17 × 10−2 V, indicating a significant performance improvement. Applications of the chlorine-doped ZnO nanorod arrays are substantial as they can be used in energy harvesting devices that are adopted in self-powered systems. The arrays also are used to advance nanotechnology in energy solutions.