In this work, we have focused on the influence of Gd³⁺ substitution on the structural, magnetic and electrical properties of cobalt ferrite synthesized using a sol–gel auto-combustion method. The powder X-ray diffraction analysis reveals that the Gd-substituted cobalt ferrites crystallize in a single phase spinel structure for lower concentrations of Gd³⁺, while a trace of GdFeO₃ appears as a minor phase for higher concentrations. Raman and Fourier transform infrared spectra confirm the formation of the spinel structure. Furthermore, Raman analysis shows that the inversion degree of cobalt ferrite decreases with Gd³⁺ doping. The field emission scanning electron microscopy images show that the substitution of small amounts of Gd³⁺ causes a considerable reduction of the grain size. Studies on the magnetic properties reveal that the coercivity of Gd-substituted cobalt ferrites enhances from 1265 Oe to 1635 Oe, the saturation magnetization decreases monotonically from 80 emu g⁻¹ to 53.8 emu g⁻¹ and the magnetocrystalline anisotropy constant increases from 5.8 × 10⁵ erg cm⁻³ to 2.23 × 10⁶ erg cm⁻³ at 300 K. The electrical properties show that the Gd³⁺ doped samples exhibit high dielectric constant (616 at 100 Hz) and ac conductivity (4.83 × 10⁻⁵ S cm⁻¹ at 100 Hz) values at room temperature. The activation energy is found to decrease from 0.408 to 0.347 eV with the rise in Gd³⁺ content. The impedance study brings out the effect of the bulk grain and the grain boundary on the electrical resistance and capacitance of cobalt ferrite. Gd substitution and the nano-size of cobalt ferrite enhance the electrical and magnetic properties which could enable a higher memory storage capability.