With the rapid advancement of modern technology, wearable electronic devices become more and more indispensable to daily life. However, powering them in a stable and sustainable manner remains a challenge and highly desired. In this work, we proposed a humidity-resisting triboelectric nanogenerator (HR-TENG) to harvest energy from human biomechanical movements for wearable electronics. The electrospun nanofibrous membranes were rationally tailored to eliminate the adverse effects of water vapor on the electrical output and construct a high-performance humidity-resisting triboelectric nanogenerator. It could work with improved adaptability to the environmental humidity caused by human perspiration during sport. With human biomechanical motions, such as hand tapping, the wearable HR-TENG can respectively deliver a current and voltage output up to 28µA and 345V, corresponding to a power density of 1.3W/m2 under a relative humidity 55%. It was also demonstrated to sustainably power an electronic watch, a commercial calculator, a thermal meter and light up about 400 LEDs by harvesting the biomechanical energy from human movements under different ambient humidity. And its electrical output was still at a relatively high level when the relative humidity was increased from 30% to 90%. Given a collection of compelling features of being wearable, flexible and cost-effective, the HR-TENG could be utilized as a sustainable power source to drive wearable electronics during human sport even with heavy perspiration.