With the increasing challenges of power supply for numerous sensors widely distributed on the Internet-of-Things, triboelectric nanogenerators (TENGs) become a potential distributed power solution by harvesting mechanical energy from the ambient environment. However, the energy output of traditional wired TENGs is largely dissipated by the discharge effect, resulting in low energy transfer efficiency. Herein, we proposed a paradigm-shift discharge-induced wireless nanogenerator (DWNG) for wireless power transfer (WPT) by utilizing the energy dissipated by triboelectric discharge. With low matching impedance, the DWNG demonstrated wireless mechanical energy harvesting with an energy transfer efficiency of 92.707%, which is much higher than that of the wired output energy of 27.775%. By investigating the spatial distribution of discharge-induced signal strength, we demonstrated that wireless energy was concentrated around the electrodes, and directional WPT can be realized using additional transport electrodes with low energy loss. DWNGs with both solid/solid and solid/liquid interfaces were demonstrated, with the feature of penetrating bio-tissues, suggesting the capability of the DWNG for high-efficiency wireless mechanical energy harvesting and directional WPT in various scenarios.