Given the inherent characteristics of defect-tolerant, tunable emission performance, and high extinction coefficient, lead halide perovskite nanocrystals (NCs) have attracted widespread attention as a promising material in optoelectronic fields. However, their poor structural stability greatly impedes their practical applications. Herein, a novel strategy for synthesizing stable CsPbBr3@SiO2 NCs via the hydrolytic polycondensation of (3-aminopropyl)triethoxysilane (APTES) in the presence of ionic liquids (ILs) is deliberately designed. The problems of fluorescence quenching and undesirable agglomeration of NCs resulting from ligand loss and surface erosion existing in common encapsulation methods can be effectively resolved. The fast and controllable growth of the SiO2 shell around the CsPbBr3 NCs is realized owing to the high polarity and hygroscopicity of the IL. Moreover, the dual effects of the IL for passivating the surface defects and avoiding the structural degradation of NCs during the hydrolysis process of APTES are demonstrated. As a result, CsPbBr3@SiO2 NCs with a high photoluminescence quantum yield of 85.7% and excellent stability are realized. Furthermore, this method proves to be a versatile tool to obtain CsPbX3@SiO2 NCs with different halide compositions, realizing a broad tunable wavelength from 421.2 nm to 651.6 nm. A warm white LED with a high color rending index was assembled through packaging CsPbBr3@SiO2 NCs and Cu-In-Zn-S/ZnS/PVP composites on a commercial blue chip. These findings are expected to facilitate the development of perovskite NCs, which provides access to their optoelectronic applications.