We demonstrate a fully integrated, on-chip, vacuum microtriode capable of handling voltages up to 800 V. The ability to operate at such high voltages is achieved by the addition of a 10 μm thick silicon dioxide layer to the device. The device is fabricated using microelectromechanical systems fabrication principles and utilizes carbon nanotubes as field emitters. A dc amplification factor of 600 was obtained. This is the highest value reported for carbon nanotube-enabled microtriode devices. The high voltage capability of these microscale devices will enable their use in a wider variety of applications.