<p>This investigation reveals the impact of manganese (Mn) doping on the structural, morphological, optical, and magnetic properties of triple perovskite material Sr₃Fe_2-xMn_xTeO₉ (where <i>x</i> = 0.0, 0.1, 0.3, and 0.5) was synthesized via the solid-state reaction route. X-ray diffraction (XRD) analysis reveals that as manganese (Mn) doping at the iron (Fe) site increases in the material, the tetragonal lattice volume decreases while crystallite size increases gradually, to an optimum level occurring at <i>x</i> = 0. 3. However, at <i>x</i> = 0.5, the trend reverses, indicating substantial changes in the material’s characteristics, because subsequent to <i>x</i> = 0.3, the crystal defects increase dramatically as a consequence of excessive doping. Confluence of the noted, it is apparent that the material’s solubility limit (optimal doping) is corresponding to concentration <i>x</i> = 0.3. Therefore, surpassing the limit results in unanticipated changes to the properties of the material, signifying the appearance of a new behavioural phase. It is evident that this pattern of behaviour has significantly influenced the optical and magnetic characteristics of the material. The variation in optical absorption spectra shows that the optical bandgap (<i>E</i>_g), increases from 1.44 (eV) for pure samples to 1.75 (eV) up to a concentration <i>x</i> = 0.3, followed by a decrease to 1.55&#xa0;eV at <i>x</i> = 0.5, making this Mn-doped perovskite material a potential candidate for photovoltaic and solar cell applications. The material’s ferromagnetic behaviour resembles the trend, with coercivity values ranging from 2.03 to 2.61 (k Oe) and a squareness ratio below 0.5 demonstrating its soft magnetic nature, making it appropriate for magnetic storage, spintronics, and other magnetic devices.</p>