Eco-friendly and sustainable energy harvests that can alleviate concerns on the energy crisis and environmental pollution are in demand. Exploiting nature-derived biomaterials is imperative to develop these carbon-neutral energy harvesters. In this study, lignin/polycaprolactone nanofiber (NF)-based triboelectric nanogenerators (TENGs) are fabricated using an electrospinning technique. Nanotextured morphology of electrospun lignin/polycaprolactone NFs and wettability modification of lignin into hydrophilicity can significantly enhance electron transfer between tribopositive and tribonegative materials, resulting in the highest energy-harvesting efficiency in their class. The output voltage of the lignin-based TENG exceeds 95 V despite relatively low tapping force of 9 N and frequency of 9 Hz. Various mechanical and physicochemical characterizations, including scanning electron microscopy (SEM), nuclear magnetic resonance (NMR) spectroscopy, X-ray diffraction (XRD) analysis, Fourier transform infrared (FTIR) analysis, and atomic force microscopy (AFM), are performed, confirming the mechanical durability, biocompatibility, and industrial viability of lignin-based TENG developed here.