Moving boundaries of electric double layer at solid–liquid interface enables unprecedented persistent energy conversion and provokes a kinetic photovoltaic effect by moving an illumination region along the semiconductor‐water interface. Here, we report a transistor‐inspired gate modulation of kinetic photovoltage by applying a bias at the semiconductor‐water interface. The kinetic photovoltage of both p‐type and n‐type silicon samples can be facilely switched on/off, stemming from the electrical‐field‐modulated surface band bending. In contrast to the function of solid‐state transistors relying on external sources, passive gate modulation of the kinetic photovoltage is achieved simply by introducing a counter electrode with materials of desired electrochemical potential. This architecture provides the ability to modulate the kinetic photovoltage over three orders of magnitude and opens up a new way for self‐powered optoelectronic logic devices.