<p>Garnet-structured oxides have emerged as compelling candidates in the realm of energy storage due to their crystallographic resilience and compositional versatility. This investigation delves into the dielectric and conduction behavior of two sol–gel-derived cubic garnets—Gd₃Ce₂Al₃O₁₂ (GCAG) and Gd₃Fe₂Al₃O₁₂ (GFAG) sintered at 1100 °C and 950 °C, respectively. Phase purity and microstructural coherence were validated via Field Emission Scanning Electron Microscopy (FESEM) and Fourier Transform Infrared (FTIR) spectroscopy. At 30 °C, GCAG exhibited a DC conductivity of 2.66 × 10^–⁵ S·m^–1, while GFAG registered 1.80 × 10^–5 S·m^–1. Thermally activated conduction regimes—diffusion, activation, and ionization—were quantified through Arrhenius analysis, yielding activation energies of 0.65 eV, 0.60 eV, and 0.58 eV for GCAG, and 0.47 eV, 0.45 eV, and 0.43 eV for GFAG. Dielectric spectroscopy revealed non-Debye relaxation dynamics, indicative of spatially heterogeneous polarization processes. Impedance analysis further resolved distinct contributions from grains and grain boundaries, elucidating the multiscale transport phenomena intrinsic to these garnet matrices. Collectively, the findings underscore the functional potential of GCAG and GFAG in next-generation energy conversion and storage devices.</p> Graphical Abstract <p></p>