The development of wood-based materials for energy harvesting, particularly triboelectric nanogenerators (TENGs), has recently attracted significant attention. Traditional strategies for wood-based TENG primarily rely on delignification to enhance tribo-positivity, overlooking the intrinsic potential of lignin and necessitating the use of fluoropolymers to maintain performance. In this study, the native lignin within the wood matrix is used to create a superhydrophobic, fully wood-based tribonegative material (referred to as Lig-wood), functioning as a liquid–solid triboelectric nanogenerator (L–S TENG) upon contact with water. Through a process of pretreatment and in-situ regeneration, lignin undergoes migration, assembly, and redistribution within the wood's hierarchical architecture. This results in enhanced hydrophobicity (water contact angle 148°) and efficient surface charge transfer. The morphological and chemical changes significantly boost Lig-wood's tribonegative performance, achieving a 7.5-fold increase in voltage and a 6-fold increase in current compared to unmodified wood. The Lig-wood powers LEDs and digital timers under simulated rainfall, demonstrating its functionality as green energy harvesting material. Importantly, the surface-localized lignin imparts self-cleaning and antimold properties, supporting the potential for long-term, outdoor use. By leveraging the inherent functionalities of lignin, this approach presents a sustainable strategy for rain-driven energy harvesting, representing a significant advancement in green and renewable energy technologies.