Recent advances in the precise control of electromagnetic and transport properties, and the miniaturization of electronic devices, have introduced new prospects in the development of practical quantum computing. Double perovskites have gained particular attention in spintronic applications due to their structural stability, non-toxicity, and inherent spin polarization. In this study, we explore the effect of Ru 4d-electrons on the magnetic properties of Ba2XRuO6 (X = Y, Lu, Sc) using first-principles calculations within the WIEN2k framework. The calculated lattice constants for Ba2XRuO6 (X = Y, Lu, Sc) using PBEsol-GGA are comparable to reported experimental values. The calculated formation energies (ΔHf) of −2.88, −2.61, and −2.43 eV (for X = Y, Lu, and Sc, respectively) confirm thermodynamic stability. Band structure and density of states analyses reveal that all compounds are ferromagnetic semiconductors. All compounds exhibit ferromagnetic semiconducting behavior, and the bandgap increases with pressure up to 4 GPa. The observed magnetism arises from hybridization effects, crystal-field interactions, and exchange coupling. Optical analysis shows strong visible-light absorption, and transport parameters evaluated from 300 to 800 K highlight notable thermoelectric potential. These findings establish Ba2XRuO6 (X = Y, Lu, Sc) as promising candidates for spintronic and thermoelectric applications.