Since the invention of the first triboelectric nanogenerator (TENG), more and more attention has been focused on this energy harvesting device due to its wide range of energy sources, low cost, and high reliability. There are many factors that affect the output performance of triboelectric nanogenerators, including the surface structure and composition of the friction pair material, frictional motion conditions, environmental factors, structure of the device and composition of the circuit. Especially for solid-solid triboelectric nanogenerators, ambient humidity has a significant impact on their output performance, which not only affects the energy harvesting efficiency and working reliability of triboelectric nanogenerators, but also greatly reduces their practical application range, especially in high humidity areas. Typically, ambient humidity accelerates the transfer, neutralization or dissipation of triboelectric charges on the friction surface, resulting in lower output of triboelectric nanogenerators. On the one hand, in a high-humidity environment, water molecules in the air are adsorbed on the surface of the friction pair to form a conductive water film, which can increase the conductivity of the friction interface and enable rapid transfer or neutralization of triboelectric charges. On the other hand, water molecules in the air accelerate the dissipation of charges on the friction surface during the migration process. Therefore, in previous reports, the output performance of solid-solid triboelectric nanogenerators generally decreases with increasing humidity, which greatly limits its practical application for energy harvesting in high-humidity environments. To solve this problem, β-cyclodextrin (β-CD) was introduced on the surface of thermoplastic polyurethane (TPU) film by molecular self-assembly to increase the number of hydroxyl groups to enhance the contact electrification (CE) performance of modified polyurethane molecules in a high-humidity environment. β-Cyclodextrin was a hydroxyl-rich bio-based macromolecule, which could spontaneously form hydrogen bonds with water molecules in the environment under high humidity, thereby immobilizing the water molecules on the surface of modified polyurethane. The bound water fixed on the surface of the polyurethane participated in triboelectric charging with the polyurethane as a whole. Since water was very triboelectrically positive, and polyurethane was also a triboelectrically positive material, the triboelectrically positive superposition effect of the two ultimately led to an increase in the electrical output of the modified polyurethane-based TENG. In addition, the surface of the modified polyurethane film was patterned, which not only greatly increased the contact area between polyurethane and PTFE during triboelectric electrification, but also improved the separation speed of the two, which further improved the electrical output performance. When the humidity increased from 15% to 95%, the short-circuit current of the TPU-based TENG increased by 432%. The electrical output of the modified TPU-based TENG was increased by 409% compared with the pure TPU-based TENG in a high-humidity environment. This TENG could light up 248 LEDs in the state of continuous spraying of water droplets, showing excellent moisture resistance. Besides moisture resistance, the improved electrical output of the modified TPU-based TENG also benefited from the introduction of β-cyclodextrin to increase the dielectric properties of the TPU film, which enabled more positive charges and storage in the triboelectric process. Due to the high performance of the modified TPU-based TENG under high humidity, this smart self-powered system can efficiently harvest wind energy in the marine environment and store energy by converting wind energy to power small electronic devices.