Zinc oxide (ZnO) is widely employed for multifunctional applications, including memristors, and has garnered substantial interest for its potential applications in next-generation integrated memory and neuromorphic computing. However, previous ZnO based memristor device studies have shown unsatisfactory performance, due to the large number of defects and low crystallinity in ZnO films deposited through several methods. This study proposes a method to modulate oxygen vacancies by doping, and subsequently confirms optimum defects at 0.14 at % Er doping. A highly crystalline Er doped ZnO (EZO) film was prepared using sputtering at room temperature for utilization as a resistive switching layer for a memristor device prepared on a transparent ITO substrate. The prepared memristor exhibited excellent forming-less uniform switching performance with endurance exceeding 10 4 cycles and stable retention for 10 7 s. Forming-free resistive switching in this device was driven by an interface type model to modulate oxygen vacancies. The remarkable EZO memristor switching characteristics suggests outstanding potential for next generation memory applications with remarkable stability, reproducibility, and reliability.