Herein, we report a comprehensive temperature-dependent investigation of the structural, conductivity, dielectric, and electrical transport characteristics of ultrawide bandgap ZnGa2O4, prepared via a solid-state route, to explore its suitability for high-temperature power electronic applications. The Rietveld refinement of X-ray diffraction (XRD) reveals a polycrystalline single-phase cubic spinel structure (space group Fd3̅m (No. 227), maximum entropy method (MEM) pattern of 220, and crystal shapes in the Brillouin zone of ZnGa2O4. The lattice vibrational modes in the low and high frequency bands at ∼530.32 cm−1 and 662.34 cm−1 correspond to metal-oxide stretching vibrations of the octahedral MO6 unit (Ga-O, Ga-O-Zn bridging) and tetrahedral MO4 unit (primarily Zn-O) of ZnGa2O4. The strong absorption in the deep ultraviolet (DUV) region with sharp absorption edges around 250–280 nm confirms the ultrawide bandgap ∼4.88 eV of ZnGa2O4 powder with average crystallite sizes ∼ 4.02 ± 0.04 µm. The complex impedance analysis and the Nyquist plots (Z′vs.Z′′) reveal both grain and grain boundary contributions in a single semicircular arc with thermally activated charge transport at elevated temperatures. The activation energy for conduction was calculated to be 0.885 eV for both grain and grain boundaries. The electric modulus study suggests a non-Debye type relaxation process and the distribution of relaxation time associated with the localized charge carriers with activation energy 0.92 eV. The frequency-dependent ac conductivity follows a low-frequency dispersing modified Jonscher’s power law, and the temperature dependence frequency exponent (n) describes the overlapping large polaron tunneling conduction mechanism between 573 and 773 K. The DC activation energy was determined to be 0.85 eV by Arrhenius fitting. The dielectric constant (εr) exhibits a strong dispersion at the low frequency regime due to Maxwell-Wagner type interfacial polarization, with an utmost value of 392 with low dielectric loss∼11.2 at a temperature of 773 K. The current-voltage characteristics demonstrate that the Schottky emission is the dominant conduction mechanism at high electric field and high temperatures, with trap energy level (φB) ∼0.77 eV. These results offer a comprehensive understanding of the high-temperature electrical response of ZnGa2O4 and dielectric suitability for high-power electronic device applications in harsh environments.