Spintronic is an emerging field of advanced technology that controls the spin of electrons to transfer, handle, and store data simultaneously at a very fast rate. To improve it further, we have systematically studied the electronic behavior, ferromagnetism, and thermoelectric characteristics of BaFe2(S/Se/Te)4 spinel's. The optimization analysis shows the ferromagnetic states release more energy as compared to the antiferromagnetic states. Therefore, the studied compounds are existing in ferromagnetic states. The Heisenberg model is employed to calculate the spin polarization and Curie temperature to confirm above room temperature ferromagnetism. Furthermore, the nature of ferromagnetism, density of states, band structures, exchange constants and exchange energies, hybridization, crystal field energy, and double ex-change model are addressed briefly. Shifting of the magnetic moment from Fe to Ba and S/Se/Te sites reveals that ferromagnetism is credited to the spin of electrons rather than the clustering of magnetic ions (Fe). Moreover, the thermoelectric parameters like Seebeck coefficient, conductivities, and power factor for spin -up (up arrow) and spin-down (down arrow) are explored to reveal how electron spin is affected by thermal parameters and for energy harvesting.(c) 2023 Elsevier B.V. All rights reserved.