<p>The demand for flexible, biodegradable, and eco-friendly energy harvesters has intensified with the growth of wearable and sustainable electronic systems. This study reports the development of a triboelectric nanogenerator (TENG) based on sodium alginate (SA) and its nanocomposites incorporating zinc oxide (ZnO), cobalt oxide (Co₃O₄), and a hybrid ZnO–Co₃O₄ system. Nanocomposite films were successfully prepared, with structural, morphological, and spectroscopic characterizations evidencing the effective integration of metal oxide nanoparticles into the SA framework. The addition of nanofillers enhanced crystallinity, interfacial polarization, and dielectric performance. Triboelectric characterization revealed that the SA/ZnO–Co₃O₄ composite exhibited the highest peak-to-peak voltage output, attributed to synergistic effects between ZnO and Co₃O₄. The voltage generation was driven by periodic contact and separation between triboelectric layers. The improved electrical behavior and compositional tunability of these nanocomposites suggest their promising applicability in sustainable energy harvesting and self-powered sensing devices. This work provides an effective strategy for advancing biodegradable TENGs through the incorporation of multifunctional nanofillers.</p>