In this study, we present a comprehensive numerical investigation of the modulation of the Schottky barrier in cesium lead bromide (CsPbBr3) perovskite, focusing on the role of internal ionic charge carriers. We observe the pronounced hysteretic behavior in the currentvoltage (I–V) characteristics of a metal-perovskite-metal configuration, where a 100 nm thick perovskite layer is sandwiched between chemically inert Schottky contacts. The inert nature of these contacts allows for the accumulation of mobile ions at the contact-perovskite interface without introducing secondary ion injections, thereby preventing any conducting filament formation. By implementing a one-dimensional drift-diffusion model, we simulate the dynamic evolution of mixed ionic-electronic charge carriers during I–V measurements. Our findings reveal that resistive state switching (RSS) is predominantly influenced by ion accumulation at the interfaces, which effectively modulates the Schottky barrier and increases carrier tunnelling probability. Additionally, our analysis highlights the significance of polarized accumulated ions in achieving a more precise interpretation of experimental I–V curves.