Flexible and wearable electronics can directly interact with the human body and environment. Fiber-based electronics offer breathability, comfort, flexibility, and light weight, but face challenges in reliable power supply. Triboelectric nanogenerators (TENGs) address this by harvesting mechanical energy with high output density. In this study, a single-electrode TENG (SE-TENG) was fabricated on a fiber substrate using spray-coated copper nanosheet (Cu NS) film as the electrode and PDMS as the dielectric via capillary tube assisted coating (CTAC). The dielectric infiltrated the Cu NS film’s voids, increasing interfacial area and charge induction. By controlling Cu NS thickness, the structure was optimized, enhancing output, flexibility, and stability. This method can be extended to fiber-based self-powered sensors for tactile and environmental detection, while the hierarchical porous Cu NS film also offers EMI shielding and thermal management potential.