We investigated the effects of neodymium (Nd) doping on the crystal structure, surface morphology, and piezoelectric properties of ZnO, and applied Nd doping to nanogenerators fabricated using polydimethylsiloxane (PDMS). In this study, Nd was doped into ZnO nanopowders at different doping concentrations (5, 10, 15, and 20 mM) by a chemical coprecipitation method. In this method, 30 wt% Nd-doped ZnO nanopowders were uniformly dispersed in PDMS and deposited onto indium tin oxide-polyethylene terephthalate substrates by spin coating to fabricate flexible nanogenerators (FNGs). X-ray diffraction analysis results confirmed the complete incorporation of Nd into the ZnO lattice. Scanning electron microscopy revealed distinct morphological characteristics. Nd-doped ZnO showed a conical columnar morphology with significantly increased nanorod length. Energy-dispersive X-ray spectroscopy confirmed the presence of Zn and O, and Nd peaks in the Nd-doped ZnO samples, verifying the successful doping of Nd into the ZnO lattice. The piezoelectric output performance of FNGs was evaluated by finger tapping at a frequency of 1.5 Hz. The results demonstrated a pronounced enhancement in output voltage at the optimal Nd-doping concentration of 15 mM, attributed to the enhanced piezoelectric effect induced by Nd incorporation.