In the present research work, Mg 2+ is inserted into Zn 0.4 Co 0.6-x Mg x Fe 1.9 La 0.1 O 4 (X = 0.00, 0.15, 0.30, 0.45, 0.60) soft ferrites prepared by the co-precipitation method. Structural, optical, vibrational, dielectric, electrical and magnetic properties were explored by XRD, SEM, UV, FTIR, SMU two probe, Raman, LCR and VSM methods respectively. XRD pattern revealed the formation of cubic spinel structure in all fabricated nanoferrites by the replacement of Co 2+ ions with Mg 2+ ions. UV-Vis also verified the substitution. The declining nature of optical band gap in the range of 2.65 – 1.85 eV were observed by UV-Vis proving the Mg 2+ ions replacement. Uniform spherical shaped nanoparticles were inspected by SEM investigation in form of microimages confirming the XRD outcomes. DC Electrical resistivity showed remarkable decreasing trend with the enhancement of Mg 2+ concentration from 4.61 x 10 9 to 5.39 x 10 6 Ω-cm as Mg 2+ is more conductive than Co 2+ . Five active phonon modes of Raman were examined by Raman spectroscopy. Dielectric parameters including dielectric losses and impedance demonstrated diminishing trends with the enrichment of Mg 2+ contents. Various magnetic parameters such as magnetic moment (μ B ), anisotropy constant (K), initial permeability (μ i ), Y-K angles (α y-k ) and microwave frequency (ω m ) were disclosed for all nanoferrites. Coercivity (H c ), squareness (SQ), remanance (M r ) and saturation magnetization (M s ) all illustrated significant reducing trends with the addition of Mg 2+ contents. Hence fabricated spinel ferrite materials are highly acceptable in microwave devices and in electrical transformers to remove eddy current losses.