<p>Nanocrystalline Bi_1−<i>x</i>Gd_<i>x</i>Fe_1−<i>x</i>Cr_<i>x</i>O₃ (<i>x</i> = 0.00, 0.04, 0.08, 0.12, 0.16) samples were fabricated via sol–gel autocombustion. x-Ray diffraction analysis (XRD) confirmed a single-phase rhombohedral structure. Crystallite size ranged from 30&#xa0;nm to 25&#xa0;nm, emphasizing their nanoscale characteristics. The lower bulk density compared with the x-ray density indicated the presence of pores. Lattice constants were computed with Cell software, indicating that substituting Bi³⁺ with the smaller Gd³⁺ ions resulted in modifications to the lattice structure. Fourier-transform infrared (FTIR) spectra revealed absorption bands between 400 cm⁻¹ and 600&#xa0;cm⁻¹, with shifts observed as the Gd concentration increased, signifying doping effects on the structure. A decrease in the frequencies of both <i>ν</i>₁ and <i>ν</i>₂ bands was observed, attributed to the disruption of the Fe³⁺–O²⁻ bond and the rearrangement of cations due to Gd incorporation. Dielectric studies performed at room temperature within the 1–3&#xa0;GHz range revealed a decrease in both real and imaginary parts of permittivity as frequency increased, consistent with the Maxwell–Wagner polarization model. At higher frequencies, the alternating-current (AC) conductivity increases substantially owing to the contribution of grains and enhanced polarization at neighboring sites. The sample with <i>x</i> = 0.16 exhibited low dielectric losses of 0.21 GHz at 3&#xa0;GHz. The decrease in the quality factor is linked to a rise in loss caused by the formation of pores within the grains. Moreover, for <i>x</i> = 0.16, a reflection loss of −66.57&#xa0;dB was measured at 0.98&#xa0;GHz. These findings highlight the potential of these materials for cutting-edge uses, especially in multilayer chip inductors and high-frequency microwave systems.</p>