<p>In this research work, cobalt-doped barium hexaferrites of composition, Ba_1-xCo_xFe₁₂O₁₉ (<i>x</i> = 0.2, 0.4, and 0.6) are fabricated via the sol-gel auto-combustion (SGC) method to investigate the morphological, structural, optical, surface, and magnetic traits. This research is performed to analyze the effect of the high cobalt doping at the lattice sites of barium cations. The magneto-plumbite crystal structure with a small trace of α-Fe₂O₃ is confirmed via the XRD analysis. An increase in the values of crystallite size is observed with the increasing cobalt doping. FESEM show the formation of well-defined surface morphology with the aggregated grains. The mesoporous structure of cobalt doped barium hexaferrites are confirmed through the BET analysis. The existence of nine Raman active vibrational modes shows the formation of hexagonal structure for the prepared barium hexaferrites. The oxidation states of every element present in the synthesised specimens are confirmed by the XPS analysis. At room temperature, with the increasing cobalt doping, the values of coercivity (H_c) and saturation magnetisation (M_s) decreases from 2368 to 1542 Oe and 43.11 to 25.12 emu/g. Therefore, in this research work, the admirable values of M_s, H_c, and surface area are making these hexaferrites as the useful candidate for the recording media and environmental applications.</p> Graphical Abstract <p></p>