To investigate the reproducibility and I–V non-linearity characteristics in resistive-switching random-access memory (RRAM), we studied the switching characteristics through Pt/TiO₂ interface control using a non-stoichiometric TiO_2−x/TiN interface formation in a resistive switching Pt/TiO₂/TiN stack. Using the TiO_2−x/TiN interface instead of the TiO₂/TiN interface induced nearly forming-free switching, decreased the reset current, suppressed the gradual reset process, and resulted in faster switching by electric pulse. These results indicate that the Pt/TiO₂ interface experienced reduced oxygen-vacancy-mediated switching. The discrepancy between the reduced oxygen-vacancy-mediated switching and the initially large number of oxygen vacancies can be resolved via the oxygen vacancy distribution dependent field effect. To clarify this process, we performed reaction-diffusion-drift model simulations. The drift velocity, which was calculated using the vacancy distribution, described the dynamic movement, and the simulation results supported the experimentally observed faster switching response. The field effect, which provided successive feedback between the drift velocity and vacancy distribution, can potentially be exploited to generate vacancy-designed devices.