Nanoscale superlattice (SL) structures have proven to be effective in enhancing the thermoelectric (TE) properties of thin films. Herein, the main phase of antimony telluride (Sb₂Te₃) thin film with sub-nanometer layers of antimony oxide (SbO_x) is synthesized via atomic layer deposition (ALD) at a low temperature of 80 °C. The SL structure is tailored by varying the cycle numbers of Sb₂Te₃ and SbO_x. A remarkable power factor of 520.8 µW m⁻¹ K⁻² is attained at room temperature when the cycle ratio of SbO_x and Sb₂Te₃ is set at 1:1000 (i.e., SO:ST = 1:1000), corresponding to the highest electrical conductivity of 339.8 S cm⁻¹. The results indicate that at the largest thickness, corresponding to ten ALD cycles, the SbOx layers act as a potential barrier that filters out the low-energy charge carriers from contributing to the overall electrical conductivity. In addition to enhancing the scattering of the mid-to-long-wavelength at the SbO_x/Sb₂Te₃ interface, the presence of the SbO_x sub-layer induces the confinement effect and strain forces in the Sb₂Te₃ thin film, thereby effectively enhancing the Seebeck coefficient and reducing the thermal conductivity. These findings provide a new perspective on the design of SL-structured TE materials and devices.