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SnTe has received considerable attention as an environmentally friendly alternative to the representative thermoelectric material of PbTe. However, excessive hole carrier concentration in SnTe results in an extremely low Seebeck coefficient and high thermal conductivity, which makes it exhibit relatively inferior thermoelectric properties. In this work, the thermoelectric performance of p-type SnTe is enhanced through regulating its energy band structures and reducing its electronic thermal conductivity by combining Bi doping with CdSe alloying. First, the carrier concentration of SnTe is successfully suppressed via Bi doping, which significantly decreases the electronic thermal conductivity. Then, the convergence and flattening of the valence band by alloying CdSe effectively improves the effective mass of SnTe while restraining its carrier mobility. Consequently, the electronic thermal conductivity is markedly reduced. Finally, a maximum ZT of ~ 0.87 at 823 K and an average ZT of ~ 0.51 at 300-823 K have been achieved in Sn0.96Bi0.04Te-5%CdSe. Our results indicate that decreasing the electronic thermal conductivity is an effective means of improving the performance of thermoelectric materials with a high carrier concentration.