The synthesis of single-crystalline ZnGa2O4 spinet phosphor with intense ultraviolet-emitting properties through a novel single-source inorganic precursor route is reported. This synthetic approach involves the calcination of a Zn-Ga layered double hydroxide precursor followed by selective leaching of the self-generated zinc oxide. Material characterization has been presented by chemical analysis, X-ray diffraction analysis, thermogravimetric-differential thermal analysis, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, electron paramagnetic resonance, nuclear magnetic resonance, extended X-ray absorption fine structure analysis, UV-vis, and photoluminescence measurements. The results indicate that a single-crystalline ZnGa2O4 spinet with an average particle size of around 150 nm has been obtained at a lower calcination temperature and shorter calcination time compared with that with the high-temperature solid-state reaction method, based on the fact that the large amount of highly dispersed ZnO particles generated during the high-temperature calcination of the single-source inorganic precursor has a remarkable segregation and inhibition effect on the growth of ZnGa2O4 spinel. Furthermore, it has been confirmed that that Ga3+ ions locate not only on the octahedral sites but also on the tetrahedral sites in the matrix of the ZnGa2O4 spinel structure, and the Ga-O coordination environment has a great influence on the photoluminence of ZnGa2O4 phosphors.