<p>This research mainly examined the structural, molecular dynamics simulations, powder diffraction analysis, electronic, optical, elastic, mechanical, and thermoelectric attributes of CsTaO₃, CsTaO_3−xS_x, CsTaO_3−xSe_x, and CsTaO₂+V_O. Our results demonstrate that these compounds maintain a cubic phase. Powder X-ray diffraction indicates a shift of diffraction peaks towards the lower angles attributed to the expansion of the crystalline lattice, and changes in lattice properties of the material. The molecular dynamics exhibit consistent oscillations around an average value, pointing the entire system is in the state of thermal equilibrium. Doping with S and Se or introducing oxygen vacancies in CsTaO₃ leads to a reduction in the bandgap value, shifting it towards the infrared spectrum. The optical characteristics of CsTaO₃, CsTaO_3−xS_x, CsTaO_3−xSe_x, and CsTaO₂+V_O have been extensively examined up to the 14&#xa0;eV energy range. The significant photon absorption occurs in the ultraviolet domains. Our research demonstrates that these compounds maintain their cubic structure and have remarkable mechanical durability, showcasing ductility. The presence of significant positive Seebeck coefficients suggests that holes are the primary charge carriers in S/Se doped CsTaO₃, while with the oxygen vacancy, electrons are predominant carriers. The CsTaO₃, with a band gap of 2.778&#xa0;eV, together with its doped variants CsTaO_3−xS_x, CsTaO_3−xSe_x, and CsTaO₂+V_O, are notably appropriate for optoelectronic and thermoelectric devices.</p>