Single-phase Bi2MO6 (M=Mo, W) glass-ceramics with photocatalytic activity were obtained by one-step heat treatment of the 51B2O3-24Li2O-7ZnO-2P2O5-1Al2O3-5Bi2O3-10MoO3/WO3 parent glasses. The thermal behaviour, phase composition, micromorphology, and network structure of the glasses were investigated, and it was observed that the crystal structure, crystallinity, and microscopic morphology of the glass-ceramics have a significant effect on the photocatalytic activity. XRD and SEM results confirm the precipitation of the monoclinic Bi2MoO6 and orthorhombic Bi2WO6 crystals, which are nano-spherical and 3D dumbbell-like structures, respectively. The prepared glass-ceramics exhibit a strong absorption in the UV-Vis region. The photocatalytic activity of the Bi2MO6 (M=Mo, W) glass-ceramic powders is evaluated by methylene blue dye under UV irradiation. Under the same conditions, the Bi2WO6 glass-ceramic powders exhibit a higher photocatalytic activity than the Bi2MoO6 glass-ceramic powders. The Bi2WO6 glass-ceramic powders achieve a 73% degradation of methylene blue dye after 150 min of irradiation. The difference in photocatalytic activity is mainly related to the crystal structure, crystallinity, and micromorphology of the glass-ceramics. The prepared Bi2WO6 glass-ceramic can be used as a photocatalyst for wastewater treatment.