<p>Transition metal thermoelectric oxide materials are an exciting class of materials owing to their high thermal stability, cheap and lower level of toxicity. Though numerous exciting thermoelectric oxide materials have been investigated so far, decreasing the lattice thermal conductivity while maintaining the high electrical conductivity to get efficient thermoelectric materials is still a challenge. Furthermore, several oxide materials are not well investigated as yet for their potential to transform waste heat into electrical power through the Seebeck effect. Herein, we report the structural and thermoelectric properties of the Bi₂Sr₂Co₂O_y <i>p</i>-type ceramic with layered structure has good potential for high-temperature thermoelectric (TE) applications. A series of Bi_2-2<i>z</i>Na_2<i>z</i>Sr₂Co_2-<i>z</i>Mo_<i>z</i>O_<i>y</i> (0 ≤ <i>z</i> ≤ 0.09) polycrystalline ceramics have been fabricated through solid-state reaction procedure. X-ray powder diffraction (XRD) data displayed that all compounds are single phase and contain misfit-layered crystal structure of consecutively arranged rock salt-type BiSrO₂ and hexagonal-type CoO₂ sheets. It is observed that Na, Mo co-doping in the Bi₂Sr₂Co₂O_y material is a very good scheme for refining the high-temperature TE properties owing to synchronized increase in the electrical conductivity (<i>σ</i>) and the Seebeck coefficient/thermopower (<i>S</i>), and reduction in the total thermal conductivity (<i>κ</i>_Total). Consequently, the highest TE power factor (<i>PF</i>) value of about 2.13 × 10⁻⁴&#xa0;Wm⁻¹&#xa0;K⁻² is attained for <i>z</i> = 0.09 composition at 1000&#xa0;K temperature. The corresponding TE figure-of-merit (<i>zT</i>) for this compound is found to be ~ 0.28 at 1000&#xa0;K. </p>