This paper presents for the first time a high-voltage MEMS plasma switch for boosting the energy transfer efficiency of conditioning circuits for triboelectric nanogenerators (TENGs). The novel MEMS switch has a narrow-hysteresis loop for a permanent high-efficiency energy conversion thanks to the combination of electrostatic actuation and plasma-discharge. At the same time, the converted energy is automatically transferred to a low-voltage reservoir through a buck converter. The experimental results show that the MEMS switch improves the harvesting efficiency by two orders of magnitude (145 times) compared to the conventional full-wave rectifying circuit architecture.