The　existence　of　Ge　vacancy　induces　an　inherently　hole　concentration　up　to　1021　cm−3　in　pristine　thermoelectric　GeTe,　which　results　in　a　need　of　∼10　%　aliovalent　dopants　for　optimization.　However,　the　extra　carrier　scattering　by　the　dopants　would　notably　deteriorate　the　carrier　mobility.　In　this　work,　CuSbTe2-alloying　is　revealed　to　increase　the　formation　energy　of　Ge-vacancy,　leading　to　a　rapid　reduction　in　hole　concentration　down　to　1.3　×　1020　cm−3　but　with　a　mobility　above　100　cm2/V-s.　Along　with　a　further　Pb-substitution　at　Ge　sites　for　lattice　thermal　conductivity　reduction　and　band　alignment,　a　peak　figure　of　merit　zT　of　∼2.4　at　625　K　is　eventually　realized　in　the　rhombohedral　structure,　leading　to　a　specific　power　density　of　as　high　as　70　W/m　and　a　conversion　efficiency　of　∼10　%　under　a　temperature　difference　of　302　K.　This　illustrates　r-GeTe　as　truly　efficient　thermoelectrics　particularly　for　low-grade　heat　recovery　applications.　©　2024