Research into efficient thermoelectric materials has gained traction recently be cause of their applications in converting waste heat into electricity. Chalcogenide and transition metals are among emerging classes of materials for potentials thermoelectric applications. In this work, we employ first-principle calculations and the Boltzmann transport equation along with self-consistent phonon theory to evaluate the thermoelectric performance of barium chalocgenide perovskites BaBX3 (B= Zr,
Hf and X= S, Se) in the orthorhombic perovskite phase, as well as BaZreS3 in the needle-like phase. Vibrational properties were investigated through the phonon dispersion, mode Gruneisen parameters and lattice thermal conductivity to understand and measure the anharmonicity in the systems. The carrier transport properties including the Seebeck coefficient, electric conductivity and the electron contribution to thermal conductivity were evaluated. We report ultra low lattice thermal conductivity of κl = 1.23W/mK for BaHSe3 at T=300K by including high order phonon scattering events. A maximum power factor of 1.16 mW/mK2 was achieved at high n-doping concentration, resulting in a thermoelectric figure of merit zT = 0.2 for BaHSe3.