In living organism, voltage-gated potassium channels play a crucial role and are largely responsible for various vital movements. For life science, it is significant and challenging to imitate and control the potassium ion transportation with a convenient artificial system. Here, we reported a voltage-gated ultrasensitive potassium-activated nanofluidic system using a 4'-aminobenzo-18-crown-6 molecule-functionalized funnel-shaped solid-state nanochannel. The switchlike property between open and closed states can be tuned freely by reversible immobilization and the release of potassium ions. By virtue of good reversibility and excellent stability, this system can potentially be applied in controlled drug release and biosensors.