In this work we have investigated electronic, magnetic and transport properties of rare-earth ternary compound BaTbO₃ based on density functional theory using the generalized gradient approximation. This material is found to be ground state antiferromagnetic semiconducting in nature with direct energy gap of 0.8 eV. The study of transport properties under constant relaxation time approximation (τ=10^-14) and rigid band approximation using BoltzTraP code in the temperature range 300-1200 K have found large value power factor and figure of merit 124 µW cm^-1K^-2 and 0.78 respectively at 1200 K, and can be enhanced with p-type dpoing. Which indicates the potential candidate for good thermoelectric material.