In this work, we developed a NH₃gas sensor based on polyaniline (PANI) composited with MoS₂nanosheet-coated SnO₂nanotubes (PMS) via electrostatic spinning, hydrothermal route and in-situ polymerization technique. The morphologies, nanostructures and compositions of the materials were obtained from X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Field emission scanning electron microscopy (FESEM), Transmission electron microscope (TEM) and Brunauer-Emmett-Teller method (BET). Thanks to nanostructure and the synergistic properties of PANI and MoS₂/SnO₂, the designed PMS gas sensor exhibited response signal of 10.9 towards 100 ppm NH₃at room temperature and a low detection limit of 200 ppb with good response-recovery time, good repeatability, acceptable flexibility and excellent selectivity. This study offers a versatile platform to modify PANI for highly selective detection of NH₃gas sensor at room temperature.