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Interface engineering has been employed on commercial Bi 0.5 Sb 1.5 Te 3 (BST) to obtain synergistically enhanced thermoelectric performance via incorporating amorphous Sb 2 S 3 nano spheres. [Display omitted] • Conducting interface engineering via incorporating Sb 2 S 3 in Bi 0.5 Sb 1.5 Te 3. • Decoupling thermal and electrical properties via introducing Sb/BST interfaces. • Obtaining a high zT of ∼ 1.31 at 330 K in Bi 0.5 Sb 1.5 Te 3 -0.4%Sb 2 S 3. Tremendous efforts have been focusing on the improvement of p-type (Bi, Sb) 2 Te 3 -based thermoelectric materials for commercial applications. In this study, we achieve versatile interface engineering through a surface decoration of Bi 0.5 Sb 1.5 Te 3 by amorphous Sb 2 S 3 combining with spark plasma sintering, which introduces semi-coherent Sb/Bi 0.5 Sb 1.5 Te 3 interfaces and dopes S into Bi 0.5 Sb 1.5 Te 3. Semi-coherent Sb/Bi 0.5 Sb 1.5 Te 3 interfaces strongly scatter phonons and lower energy carriers, leading to decreased thermal conductivity and increased Seebeck coefficient, while the electrical conductivity is not sacrificed due to the compromise of the slightly reduced carrier mobility by interfacial scattering and the increased carrier concentration by S doping. Benefited from the decoupled thermoelectric properties, a significantly enhanced power factor of 3345.40 μW m−1 K−2 and a low thermal conductivity of 0.78 W m−1 K−1 is obtained in Bi 0.5 Sb 1.5 Te 3 -0.4%Sb 2 S 3 , leading to a high peak zT of ∼ 1.31 at 330 K, which shows a 54% enhancement compared with pristine Bi 0.5 Sb 1.5 Te 3. Moreover, a conversion efficiency of ∼ 7.6% can be predicted in a single leg Bi 0.5 Sb 1.5 Te 3 -0.4%Sb 2 S 3 -based module under a cold side temperature of 300 K and hot side temperature of 480 K. This study paves a facile amorphous Sb 2 S 3 induced interface engineering strategy for the development of high performance (Bi,Sb) 2 Te 3 -based thermoelectric materials. [ABSTRACT FROM AUTHOR]