<p>The co-precipitation method was utilized to synthesize NiO, CoFe₂O₄, and Ba_0.5Sr_0.5Fe₁₂O₁₉ pure nanophases. The nanocomposites: (0.5NiO/0.5CoFe₂O₄), (0.5NiO/0.5Ba_0.5Sr_0.5Fe₁₂O₁₉), and (0.5CoFe₂O₄/0.5Ba_0.5Sr_0.5Fe₁₂O₁₉) were prepared by ball milling. X-ray diffraction analysis confirmed the successful synthesis of all pure samples and nanocomposites. NiFe₂O₄ appeared in the (0.5NiO/0.5Ba_0.5Sr_0.5Fe₁₂O₁₉) nanocomposite due to the reaction of α-Fe₂O₃ with NiO. Transmission electron microscopy showed hexagonal, quasi-spherical, and cubic morphologies of Ba_0.5Sr_0.5Fe₁₂O₁₉, CoFe₂O₄, and NiO, respectively. X-ray photoelectron spectroscopy demonstrated the existence of Co²⁺, Ba²⁺, Sr²⁺, Fe³⁺, Ni²⁺, Ni³⁺, and O²⁻ oxidation states in the prepared samples. The energy gap values (3.14–3.67&#xa0;eV) confirmed the semiconductor nature of the nanocomposites. The (0.5NiO/0.5CoFe₂O₄) exhibited the highest DC conductivity (0.117 S/m at 813&#xa0;K) among all nanocomposites. The activation energies were below 0.8, suggesting an electronic charge transport. The M-H hysteresis curves of all nanocomposites displayed ferromagnetic behavior. The coercivity of (0.5NiO/0.5Ba_0.5Sr_0.5Fe₁₂O₁₉) dropped dramatically (16.765 Oe), indicating a weak ferromagnetic behavior. Some important applications of the prepared nanocomposites, depending on their constituents, include supercapacitors, soft ferrites, permanent magnets, magnetic recording media, electromagnetic compatibility, and radar applications.</p>