Morphological engineering of nano- and micro-surface patterns has been considered as a key design element to achieve superior output performances in triboelectric energy harvesters. Most previous studies have focused on the surface engineering of dielectric materials rather than electrodes. In this study, a hierarchically three-dimensional (3D) copper nanowire-copper Mesh hybrid electrode (Cu NW-Cu Mesh) is reported for developing a high-performance and structurally reliable triboelectric nanogenerator (TENG). The hierarchical electrode has been embedded into a dielectric thin layer of polydimethylsiloxane (PDMS), resulting in an integrated dielectric-electrode layer that has much better structural reliability to repeatable impacts and inherits the roughened morphology of the Cu NW-Cu Mesh. The PDMS sealed Cu NW-Cu Mesh can be widely used in vertical contact-separation mode, single electrode mode, and wind-driven TENGs. Serially connected four hundred green LEDs can be lighted by free fall of a large size Cu NW-Cu Mesh based single electrode TENG. By tapping the large size TENG, a capacitor can be charged and used to power an electronic watch. The results indicate that the proposed integrated dielectric-electrode layer can be used as an effective mechanical energy harvester requiring both structural reliability and high output power under strong impacts due to large amplitude oscillations based on fluid-structure coupled dynamic instabilities.