The Ba2 GdRuO6 (BGRO) double perovskite oxide (DPO) demonstrates intriguing behavior, arising from competing antiferromagnetic (AFM) and ferrimagnetic (FiM) phases. Under the GGA+U+SOC scheme, the system exhibits an AFM ground state with a very small energy difference of −11.39 meV with FiM one. In contrast, spin modeling reveals significant magnetic frustrations along the z-axis and favors the FiM phase. Also, the magnetic phase transition discloses a Curie temperature (T_C) of 60 K. Additionally, magnetization measurements also affirm the FiM nature which lost saturation at higher temperatures, indicating a transition from FiM to paramagnetic above T_C. The electronic structure displays the semiconductor nature owing to a direct energy gap of 1.04/0.89 eV in the AFM/FiM state. The determined spin moments on the Gd(1-2)/Ru(1-2) and Gd(3-4)/Ru(3-4) ions are +6.9/+2.0 µB and −6.9/−2.0 µB in the AFM SO, respectively, while they are +6.89/−2.0 on the Gd(1-4)/Ru(1-4) ion in the FiM one. It is found that, Gd3+ and Ru4+ ions lie in +3(4f ^7) and +4(4d^4) alence state with the electronic configurations of [ fx(x2 −3y2 ) ]↑0 ↓1 [ fy(3x2 −y2 ) ]↑0 ↓1 [ fz(x2 −y2 ) ]↑0 ↓1 [ fxyz ]↑0 ↓1 [ fxz2 ]↑0 ↓1 [ fyz2 ]↑0 ↓1 [ fz3 ]↑0 ↓1 and 3 ↑ t 1 ↓ e0 ↑ e0 ↓ with spin quantum number of 7/2 and 1, correspondingly. Furthermore, the mehanical stability of the material is validated by satisfying the Born stability criteria and the ductility (B/G= 5.19). Noticeably, the presence of a positive Cauchy presis determined by the Pugh’s ratio of 66.53 GPa further supports the ionic nature of the motif. Besides, the system illustrates a positive Seebeck coefficient, indicating holes as the dominant charge carriers with the highest of 279 µV/K at 400 K. Remarkably, system achieves a high figure of merit of 0.86 at 550 K even with the inclusion of lattice thermal conductivity as well as sustaining excellent thermoelectric performance, suggesting a strong potential for elevated temperature energy harvesting applications along with spintronics.