Thermoelectric material, Ag_1−𝑥Pb_𝑚SbTe_𝑚+2 (𝑥 = 0.2, 𝑚 = 10), have been successfully prepared by high pressure method. The pressure-dependent electrical transport and thermoelectric properties of Ag_0.8Pb₁₀SbTe₁₂ were studied at room temperature. Electrical resistivity and Seebeck coefficient decreases with an increase of synthetic pressure. Thermal conductivities are nearly constant when the pressure is lower than 4 GPa. The carrier concentrations of Ag_0.8Pb₁₀SbTe₁₂ were tuned by more than a factor of 100 through changing of synthetic pressure. These results indicate that high pressure technique provides a viable and controllable way of tuning the electrical transport properties for AgPb_𝑚SbTe_𝑚+2.