Recently, the thermally stable and facilely fabricated inorganic CsPbIBr2 perovskite solar cells (PSCs) have attracted tremendous attention where the electron transport layer (ETL) is vital. However, the typical sintering temperature for the widely used electron transport material, that is, TiO2, is more than 400 °C, elevating the cost and hindering the application. Due to high electron mobility and low fabrication temperature, ZnO becomes a desirable alternative for TiO2, as the ETL in CsPbIBr2 PSCs, albeit with low open‐circuit voltage (Voc). Herein, this work introduces a trace of NH4Cl to the sol–gel‐derived ZnO precursor to decrease the work function of the ZnO film, tune the surface morphology of the perovskite film, and thus suppress the density of trap states in the CsPbIBr2 films. Consequently, full‐coverage and pure‐phase CsPbIBr2 films consisting of micron‐size and high‐crystallinity grains are obtained. More importantly, for the optimal NH4Cl‐modified ZnO, a shining improvement in Voc from 1.08 to 1.27 V boosts the champion CsPbIBr2 PSCs to obtain a power conversion efficiency of 10.16%, which is the highest value reported among pure‐CsPbIBr2 PSCs under a low fabrication temperature of 160 °C. In addition, the NH4Cl‐modified ZnO ETL reduces the severe hysteresis and increases the device stability significantly.