<p>Mg₁₋_xLi_xFe₂O₄ nanoparticles were synthesized using a cost-effective sol–gel method and systematically investigated to understand the influence of Li⁺ substitution on their structural, dielectric, and magnetic properties with relevance to advanced device applications. X-ray diffraction analysis confirmed the formation of a single-phase cubic spinel structure for all compositions, while the crystallite size decreased from 35.19 to 30.17&#xa0;nm with increasing Li content, indicating lattice distortion due to the incorporation of Li⁺ ions. Microstructural examination revealed homogeneous, well-defined grains with improved crystallinity, supporting the reliability of the synthesis approach. Dielectric studies demonstrated strong frequency-dependent behavior, primarily governed by electron hopping between Fe²⁺ and Fe³⁺ ions at octahedral sites, along with space charge polarization dominating at lower frequencies. The introduction of Li⁺ ions enhances charge carrier mobility and hopping probability, resulting in improved polarization, increased grain conductivity, and reduced grain boundary resistance. This transition from frequency-independent to frequency-dependent conductivity behavior is particularly beneficial for high-frequency applications. Magnetic measurements showed a marked improvement in performance, with saturation magnetization increasing from ~ 41.5 to 49.31 emu g⁻¹, remanent magnetization reaching 19.718 emu g⁻¹, and coercivity increasing from 198 to 221 Oe. These enhancements are attributed to cation redistribution between tetrahedral and octahedral sites, strengthening magnetic interactions. Overall, these improved multifunctional properties make Mg₁₋_xLi_xFe₂O₄ nanoparticles suitable for energy storage, high-frequency electronics, and electromagnetic device applications.</p>