<p>By employing an advanced sol-gel auto-combustion (SGC) method, we successfully fabricated the nanoscale spinel ferrites of chemical composition, MgSm_xFe_2-xO₄ (x = 0.0–0.2). A detailed structural analysis showed the defining attributes of the crystal structure of pure and doped magnesium ferrites. XRD study showed that the prepared samples exhibit the cubic phase along with the ortho-ferrite phase and also, there was a decline in crystallite size ranging from 42.67 to 32.89 nm with Sm doping. Using the FESEM analysis, the grain size was found to be 117.32 and 71.64 nm for MgFe₂O₄ and MgSm_0.02Fe_1.98O₄, respectively. FTIR spectra show two distinctive absorption bands of the prepared ferrites; the first was between 537 to 564 cm⁻¹ and the second between 403 to 437 cm⁻¹. Six Raman-active vibrational modes confirmed the cubic structure of the prepared magnesium spinel ferrites. The oxidation states of the different cations within the materials were also analysed by the XPS study. Magnetic analysis revealed an anomalous trend in magnetic parameters because of the A-B site interactions. The dM/dH analysis confirmed the multi-domain nature of the prepared samples. In addition, the undoped MgFe₂O₄ and doped MgSm_0.1Fe_1.90O₄ samples produced significant zone of inbition (ZOI) against both the <i>P. aeruginosa</i> and <i>Staphylococcus aureus</i> bacterial strains. Thus, the tailored magnetic, antibacterial and the crystal structure traits of the MgSm_xFe_2-xO₄ spinel ferrites make them promising candidates for the magnetic storage, and the antibacterial applications. The ehanced surface area also enable their potential use in catalysis and water treatment.</p> Graphical Abstract <p></p>