In this work, self-assembled monolayers (SAMs) of octadecyltrichlorosilane (OTS) were applied to induce the nucleation and growth of the antimony sulfide (Sb2S3) films on the functional ITO glass substrate at low temperature. The structure, morphology, and optical properties of the Sb2S3 films were investigated by X-ray diffraction, scanning electron microscopy, X-ray energy dispersive spectroscopy, and UV–vis spectroscopy. After thermal treatment at 200 °C for 1 h in air, the orthorhombic Sb2S3 was formed as a predominant phase in the deposited thin films. When the deposited films were thermally treated at 400 °C for 1 h in air, the orthorhombic Sb2S3 was decomposed and a cubic Sb2O3 was formed. The optical band energies of the as-deposited and thermally treated Sb2S3 films at 200 °C for 1 h in air and nitrogen were found to be 2.05 eV, 1.77, and 1.76 eV, respectively. As chemical templates, the OTS-functionalized SAMs played an important role in controlling the nucleation and growth of Sb2S3 films at low temperature. The results obtained from different preparation parameters applied in the present work will allow controlling the growth of the Sb2S3 films with uniform surface.