Mg-doped ZnO nano-plates were successfully prepared by the low cost wet chemical method. X-ray diffraction (XRD) pattern revealed a polycrystalline pure hexagonal wurtzite structure. Scanning electron microscopy (SEM) was used to study the morphology of the synthesized samples. Further, Energy-dispersive X-ray spectroscopy (EDS) measurement confirmed the presence of Mg elements in the ZnO matrix. The UV–visible reflectance spectroscopy was applied to study the effect of dopant on band gap of pure ZnO. The result showed a slight decrease in the band gap with Mg doping. In addition, the dielectric analyses of the obtained samples were done in a wide frequency range and electronic properties of the pure and doped samples were analyzed using various theoretical models. These results suggested that the Mg-doped ZnO nano-plates have potential applications in the optoelectronic devices. The results were analyzed in detail.