Cesium lead halide (CsPbX3, where X is Cl, Br, or I) perovskite quantum dots (QDs) hold great potential for applications in various devices, on account of their superior electronic and optical properties. However, the poor stability has severely restricted their applications. Herein, by exfoliating K4Nb6O17into niobate nanosheets (KNO NSs) and utilizing the flocculation of KNO NSs as building blocks, the CsPbBr3/K4–xNb6O17(CsPbBr3/KNO) nanocomposites were obtained via evaporation of a dimethyl sulfoxide (DMSO) solution and crystallization of CsPbBr3nanocrystals. The as-synthesized CsPbBr3/KNO nanocomposites possess sandwich-like and scroll-like heterostructures, which consist of restacked KNO NSs and CsPbBr3in the internanosheet gallery. CsPbBr3/KNO nanocomposites exhibit better exciton emission of CsPbBr3with a prolonged emission decay time with reference to the value of CsPbBr3QDs. In addition, the strong interaction at the interfaces of CsPbBr3and KNO NSs endows CsPbBr3/KNO nanocomposites with significantly improved resistance to alcohol over bare CsPbBr3QDs. This work paves a new way for utilizing oxide nanosheets as building blocks to synthesize stable all-inorganic perovskite QDs.