An Eu3+-doped novel mother glass in the K2O-SiO2-Y2O3-Al2O3 (KSYA) system was prepared by the melt-quench technique. The transparent Y3Al5O12 (YAG) glass-ceramics were derived from this glass by a controlled crystallization process. The formation of YAG crystal phase, size and morphology with the progression of heat treatment was examined by X-ray diffraction (XRD), transmission electron microscopy, field-emission scanning electron microscopy, and Fourier transformed infrared reflectance spectroscopy. The crystallite sizes obtained from XRD are found to increase with heat-treatment time and vary in the range of 35-45 nm. The photoluminescence spectra of Eu3+ ions exhibit emission transitions of 5D(0)-> 7F(j) (j=0, 1, 2, 3, and 4) and its excitation spectra show a charge transfer band around 280 nm. From these emissions, the site symmetry in the vicinity of Eu3+ ions has been found to be C-s or lower than C-s in the nanoglass-ceramics. Absorption and fluorescence spectra reveal that the Eu3+ ions are entering into the YAG nanocrystals of the glass-ceramics. The present study indicates that the incorporation of Eu3+ ions into the YAG crystal lattice enhance the fluorescence performance of the nanoglass-ceramics. We believe that this work would generate new avenues in the exploration of YAG nanoglass-ceramics in particular and other glass-ceramics of very high-temperature melting crystals in general.