Polycrystalline samples of Mg_0.5Zn_0.5-xCoxFe₂O₄ (0 ≤ x ≤ 0.5) with x varying from 0.0-0.5 synthesized by solgel auto ignition method. The X-ray diffraction analysis with Retvield refinement reveals the formation of single phase cubic spinel structure. The frequency dependent of real part of dielectric constant has been measured at room temperature and at 100 ^oC by using an ac impedance analyzer. Except x = 0.5, an increase in the dielectric constant is observed with increase in Co²⁺ substitution. Magnetic response has been seen by vibrating sample magnetometer (VSM) at room temperature. The saturation magnetization (M_S) and coercivity (H_C) increase with increasing the Co²⁺ substitution. The cation distribution estimated by Mössbauer spectroscopy shows that Co²⁺ and Mg²⁺ ions have their preference towards octahedral B site, on the other hand Zn²⁺ ions preferentially occupy tetrahedral A site, whereas Fe³⁺ ions are randomly distributed over A- and B-site. The as obtained results indicated that the substitution of Co²⁺ has brought the significant changes in the structural, electrical and magnetic properties of as prepared Mg-Zn-Co multioxide nanocrystals.