The bismuth (Bi)-substituted CuSb1-xBixSe2 chalcostibites were synthesized using the horizontal Bridgman-Stockbarger technique combined with ball milling, at temperatures ranging from 303 to 650 K. The impact of Bi substitution was observed in the thermoelectric transport properties by substituting Bi (x = 0, 0.2, 0.4, 0.6) resulted in a decreased Seebeck coefficient and higher electrical resistivity compared to the pure CuSbSe2 sample. Notably, the higher substitution level (x = 0.6) showed the enhanced properties compared to the lower levels. The pristine sample exhibited a power factor of 550 μWK−2 m−1, while the substituted samples showed the values of 20, 37 and 50 μWK−2 m−1, respectively. However, in accordance with the power factor, the pristine compound demonstrated a higher figure of merit (ZT = 0.47) compared to the existing literature values (ZT = 0.21), indicating the superior thermoelectric performance using this synthesis method.