The thermoelectric properties of Bi2Sr2Co2Ox (BSC-222) bulk materials prepared by three different processing methods, i.e., conventional sintering, hot pressing, or partial melting, were investigated and compared. The electrical current, temperature difference for Seebeck coefficient, and thermal diffusion were measured in the same direction. The hot pressing and partial melting are effective processing methods for improving the electrical transport property in BSC-222 bulk materials due to an improvement of density in hot-pressed samples or by grain growth during partial melting process. For partially melted samples, a decrease in the thermal conductivity is also observed. The highest dimensionless thermoelectric figure of merit (ZT) values have been obtained in the sample prepared by partial melting method, for which ZT has been increased by a factor of 2.7 by comparison with bulk materials prepared by conventional sintering. At 700 °C in air, ZT value reaches 0.27 for partially melted Bi2Sr2Co2Ox bulk materials. This study shows that optimized electrical and thermal transport properties can be achieved in BSC-222 bulk materials possessing microstructures with both large average grain size and appropriate bulk density.