Lead-free and eco-friendly GeTe shows a promising candidate for mid-temperature thermoelectric application. However, a low Seebeck coefficient due to its intrinsically high holes concentration that induced by Ge vacancies, and a relatively high thermal conductivity result in an inferior thermoelectric performance of pristine GeTe. However, extrinsic atoms Sb, Bi, and Y could play a crucial role in regulating the holes concentration of GeTe because of their relatively high solubility. Here we investigate the thermoelectric performance of the GeTe upon Sb doping, and demonstrate a high maximum zT value up to 1.88 could be achieved in Ge 0.90 Sb 0.10 Te as a result of the significant suppression in thermal conductivity while holding a high power factor. Where the maintained high power factor is due to the markable enhancement in S , which could be attributed to the significant suppression of holes concentration and the valence band convergence upon Sb doping; while the low thermal conductivity stems from the suppression of electronic thermal conductivity due to the increase in electrical resistivity and the lowering of lattice thermal conductivity through strengthening the phonons scattering by the lattice distortion, dislocations, and twin boundaries. Aside from the excellent thermoelectric performance, Ge 0.90 Sb 0.10 Te also shows good reproducibility, as well as thermal stability. This work confirms the Ge 0.90 Sb 0.10 Te is a superior thermoelectric material for practical application.