The transmission lines galloping severely threatens the safety operation of the power grid. A reliable operation and maintenance alternative is to monitor the transmission lines by wireless sensing and warning devices. In this work, a triboelectric nanogenerator with the double‐mass pendulum integrated spacer (DMPS‐TENG) is proposed for harvesting the galloping energy of transmission lines and powering the wireless monitoring devices. Specifically, by introducing a double‐mass pendulum system, the response frequency of the DMPS‐TENG is reduced, allowing it to harvest energy at lower frequencies in the range of transmission lines galloping (0–3 Hz). Hereby, enhancing the energy harvesting bandwidth and the efficiency. The experiments show that with the introduction of the double‐mass pendulum, the optimum frequency of the harvester is reduced from 2.4 to 1.9 Hz, enhances the harvesting bandwidth by 18%, and enables an average power output of up to 0.32 mW. Additionally, to demonstrate the practical value, a prototype is designed and fabricated to perform three different application experiments in the multi‐split transmission lines simulation system. This work presents an innovative approach for galloping energy harvesting of transmission lines, which can be used to inform further development of sensor networks and visualization of the power grid.