Oxide glasses generally have low thermal conductivity due to their disordered structures. Here, a fabrication method to provide them with high thermal conductivity while retaining their optical transparency is proposed. It consists of dispersing ∼20 μm MgO crystals in a glass matrix and matching their refractive indexes to prevent the decrease of the oxide glass optical transparency due to light scattering. The dispersion of the MgO crystals increased the thermal conductivity of the original glass by ∼50% and the new glass still exhibited optical transparency. Such MgO-dispersed glass could be successfully used in thermal management applications requiring both transparency and formability.