ZnO amorphous nanostructures in a glass matrix show unique optical properties. However, although a ZnO amorphous nanostructure can be formed in some settled multicomponent silicate glasses, the intensity of its emission is extremely weak. Here, to the best of our knowledge, we report a novel and simple zinc phosphate oxynitride glass that can display strong broadband blue emission with a short decay time due to the ZnO amorphous nanostructure in the glass matrix. The result implies that glass topological constraints are the key to forming ZnO amorphous nanostructures. The findings contribute to a deeper understanding of the formation of ZnO amorphous nanostructures in zinc-containing glass.