Highlights A new proton-promoted in situ ligand exchange strategy based on CsPbI3 quantum dots. The ligand exchange strategy maintains the quantum confinement effect of quantum dots and significantly improves the stability and photophysical properties of CsPbI3 quantum dots. The performance of light-emitting diodes based on CsPbI3 quantum dots is significantly improved, the external quantum efficiency is increased from 18.63% to 24.45%, and the half-operational lifetime is increased by 70 times.