It is vital to have high sensitivity in gas sensors to allow the exact detection of dangerous gases in the air and at room temperature. In this study, we used 2D MXenes and MoS2 materials to create a Ti3C2–MoS2 composite with high metallic conductivity and a wholly functionalized surface for a significant signal. At room temperature, the Ti3C2–MoS2 composite demonstrated clear signals, cyclic response curves to NO2 gas, and gas concentration-dependent. The sensitivities of the standard Ti3C2–MoS2 (TM_2) composite (20 wt% MoS2) rose dramatically to 35.8%, 63.4%, and 72.5% when increasing NO2 concentrations to 10 ppm, 50 ppm, and 100 ppm, respectively. In addition, the composite showed reaction signals to additional hazardous gases, such as ammonia and methane. Our findings suggest that highly functionalized metallic sensing channels could be used to construct multigas-detecting sensors that are very sensitive in air and at room temperature. The hypothesized NO2-sensing mechanism of the Ti3C2–MoS2 composite. Display omitted •Formation of Ti3C2–MoS2 composite from MXenes and MoS2.•Clear signal and concentration-dependent to NO2 gas.•Used to construct multigas-detection sensors in the air.