<p>Tailoring magnetic performance through strategic doping is critical for next-generation hexaferrite applications. This study systematically explores the structural, microstructural, and magnetic behaviours of La-Co-doped SrFe₁₂O₁₉ (Sr₁₋_<i>x</i>La_<i>x</i>Fe₁₂₋_<i>x</i>Co_<i>x</i>O₁₉, <i>x</i> = 0, 0.2, 0.3) as a function of doping concentration and sintering temperature (from 1050&#xa0;°C to 1300&#xa0;°C). XRD and subsequent Rietveld refinement confirm a stable single-phase magnetoplumbite structure with lattice contraction due to the substitution of smaller La³⁺ and Co²⁺ ions. SEM micrographs reveal hexagonal platelet-like grains, with grain size decreasing for <i>x</i> = 0.2 due to lattice strain but marginal grain growth for the sample with <i>x</i> = 0.3. Energy Dispersive X-ray Spectroscopy (EDS) confirmed the stoichiometric incorporation of La and Co into the lattice. Magnetic property measurements revealed that coercivity (H_c) decreases with increasing sintering temperature, while a marginal increase in saturation magnetization (M_s) was observed possibly due to enhanced grain growth and densification. The Optimal magnetic performance was achieved for <i>x</i> = 0.2, with higher coercivity attributed to reduced grain size and increased magnetocrystalline anisotropy. However, for <i>x</i> = 0.3, excessive doping led to grain growth and weakened superexchange interactions, reducing the coercivity. XPS analysis has shown that La and Co were successfully incorporated, leading to an increase in Fe²⁺ ions and also increase in the oxygen vacancies. These results demonstrate the critical interplay of doping and sintering temperature in tailoring the structural and magnetic properties of La-Co-doped SrFe₁₂O₁₉. The study provides valuable insights into optimizing hexaferrite materials for advanced magnetic applications.</p>