We developed a water-free atomic layer deposition (ALD) process to homogeneously deposit SbO_x using SbCl₅ and Sb-Ethoxide as precursors, and report it here for the first time. The coating is applied on Bi₂Te₃ particles synthesized via the solvothermal route to enhance the thermoelectric properties (i.e., Seebeck coefficient, thermal and electrical conductivity) via interface engineering. The amorphous character of the coating was shown by the missing reflexes on the X-ray diffractograms (XRD). A shift from the oxidation state +III to +V of the Sb species was observed using X-ray photoelectron spectroscopy (XPS), indicating increased thickness of the SbO_x coating layer. Additionally, a peak shift of the Sb 3d_5/2 + O 1s peak indicated increased n-type doping of the material. Electrical measurements of spark plasma-sintered bulk samples confirmed the doping effect on the basis of decreased specific resistivity with increasing SbO_x layer thickness. The Seebeck coefficient was improved for the coated sample with 500 cycles of SbO_x, while the total thermal conductivity was reduced, resulting in enhancement of the zT. The results distinctly show that surface engineering via powder ALD is an effective tool for improving key properties of thermoelectric materials like electrical conductivity and the Seebeck coefficient.