All-inorganic cesium lead halide perovskite quantum dots (PQDs) appear to be promising scintillators for radiation detection; however, they are suffering from poor stabilities against light, heat, and moisture. Here a strategy of using AgCl as the nucleating agent is developed to facilitate growth of CsPbBr3 PQDs in chemically inert tellurite glasses via controlled crystallization. The PQDs are uniformly dispersed and well protected in the dense glass matrix without aggregation. The nanocomposites thus obtained are featured by excellent optical transparency owing to the unique character of tellurite glass having a refractive index comparable to that of the CsPbBr3 crystal. The X-ray excited radioluminescence properties are comprehensively studied. The results show that CsPbBr3 PQD-doped tellurite glasses are highly stable against continuous X-ray irradiation and repeated heat-cooling cycles (from room temperature up to 573 K) without sacrificing their scintillation properties, thus appearing to be a potential scintillator for long-term practical applications.