Sintering by viscous flow in a “kinetic window” between Tg and Tx temperatures was used to prepare bulk glass/glass‐ceramic luminescent materials from rapidly quenched glass microspheres in the system Y2O3–Al2O3 doped with Ce3+ ions. The glass microspheres were prepared from sol–gel synthesized precursor powders in a high‐temperature methane‐oxygen flame. The crystallization of the glasses was analyzed using differential scanning calorimetry and high‐temperature X‐ray diffraction. The crystallization behavior of quenched glass microspheres was found to be strongly dependent on glass composition. The glass microspheres were consolidated into bulk material by hot‐pressing technique at a temperature of up to 1100℃ with the applied pressure 40MPa. The optimized time‐temperature‐pressure regime enables the preparation of bulk glass, and glass‐ceramic with a high fraction of crystalline Ce3+‐doped YAG phase embedded in the Al2O3‐enriched glass matrix. The glass/glass‐ceramics emit blue/yellow light with high intensity under excitation in UV and/or blue spectral region.