In this research, a two-step hydrothermal technique is used to fabricate a NO2 gas sensor based on MoS2 nanoflowers with SnO2 nanoparticles. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS), were used to determine the morphologies, nanostructures, and compositions of the materials. The nanocomposites consisting of MoS2/SnO2 demonstrated a remarkable sensing response (38.6) towards 100 ppm of NO2. Moreover, the nanocomposites showed a rapid response and recovery time (42/147 S) when exposed to 100 ppm at temperature (250 °C). The MoS2/SnO2 nanocomposites demonstrated exceptional selectivity to NO2 against CO, NH3, and H2S, as well as demonstrated good repeatability. The significant gas detection characteristics could potentially be controlled by the distinctive structures of thin layers assembled into flower-like formations of two-dimensional MoS2. The multi-joint nanostructures promote the process of transferring the electrical charge of the carrier and the response to MoS2/SnO2 and NO2. The fabricated sensors are considered as potential candidates for the commercial in the nitrogen dioxide gas-sensing applications.