Samples of Sr_1−xCe_xFe₁₂O₁₉ (x = 0.0, 0.05, 0.1, and 0.15) were synthesized by a hydrothermal process. The X-ray diffraction patterns and the Rietveld refinement method confirmed the formation of the pure nano-crystalline phase of the M-type hexaferrite for all samples, except for the x = 0.15 sample with a small CeO₂ phase. Fourier transform-infrared spectroscopy measurements showed the formation of the M-type hexaferrite. Field emission-scanning electron microscopy revealed that the prepared samples were nanoparticles that agglomerated in irregular platelets. The hysteresis loops (M–H) measured at room temperature indicated a decrease in the saturation magnetization with an increase in the Ce content. The band gap dependency on the Ce content was also studied using the UV–Vis spectra, which showed that the band gap energies were in the range of 1.37–1.51 eV. The dielectric constant and dielectric tangent loss measurements showed that the x = 0.1 sample has higher values than others.