<h2>Summary</h2> An efficient energy-management strategy is critical for the energy utilization of triboelectric nanogenerators (TENGs), of which the switch and convertor are two key parts. However, common switches only withstand limited voltage (∼10<sup>2</sup> V), while the convertors for electrostatic energy are diversely designed without standard principles. Here, we report a simple, tunable auto-spark switch to achieve energy accumulation and fast release and develop a standard design procedure of matched transformer for electrostatic energy conversion. We establish an ultrahigh voltage (over 7.5 kV) energy-management system for TENG. Ultrahigh output charge of 660 <mml:math><mml:mrow>μ</mml:mrow></mml:math>C per cycle, pulsed power density of 11.13 kW m<sup>−2</sup>, and constant power density of 291 mW m<sup>−2</sup> at 3 Hz are all achieved. With this energy-management unit, TENGs can continuously power a wireless sensors network at 1 Hz. This energy-management approach enables TENGs to present a breakthrough in practical applications.