<p>Co_0.40Cu_0.20Zn_0.40Gd_xFe_2−xO₄(x = 0, 0.025, 0.050, 0.075, 0.10) was prepared using the conventional solid-state reaction technique. The cubic spinel structure is studied through X-ray diffraction (XRD). The lattice parameters were increased from 3.08Å to 8.354Å with Gd content. Microstructural analysis indicates that the mean grain size was increased with Gd³⁺ content up to x = 0.050. The complex initial permeability determined the characteristics of magnetic properties. The real part of the initial permeability (µ_iʹ) increases with Gd³⁺ content up to x = 0.04 and then decreases. The highest µ_iʹ was observed for x = 0.050 at the optimal sintering temperature. As the Gd³⁺ concentration increased to x = 0.05, the saturation magnetization (M_s) increased from 72.70 to 78.7 emu/g. M_s was declined after x = 0.05 as a result of the potential for non-collinear spin arrangements with further increments in Gd³⁺ content. The α_Y−K values reached a minimum of 26˚ at x = 0.05, whereas n_B explores an opposite trend. The reduction of electron exchanges between Fe²⁺ and Fe³⁺ at the octahedral site led to a decrease in the dielectric constant and dielectric loss with the Gd³⁺ content. Non-Debye relaxation behavior is observed from the theoretical fitting justification of the bulk ferrite.</p>