In this article, we synthesized WO₃/WS₂ nanocomposites by facile hydrothermal synthesis followed by thermal annealing treatment and analysed its gas sensing properties. The thermal annealing process was carried out in different temperatures from 400 ℃ to 600 ℃ to form WO₃/WS₂ nanocomposite. During the thermal annealing process, the hydrothermally synthesized pure WS₂ nanosheets undergo partial oxidation constructing WO₃ on the surface developing active heterojunctions leading to increment in the sensing performance. The fabricated WO₃/WS₂ samples showed superior sensitivity and selectivity towards NO₂ gas molecules. The pristine WS₂ nanosheets showed a response of 26% towards 10 ppm of NO₂ gas with a response and recovery time of 13 s /18 s, whereas WO₃/WS₂ nanocomposite prepared by annealing at 600 ℃ showed a maximum response of around 123% with a short response time of 11 s and recovery time of 163 s. The DFT calculations were performed to understand the gas sensing performance and interfacial charge transfer between the WO₃/WS₂ nanocomposite and gas molecules. Therefore, this study demonstrates that the indigenous heterojunctions contribute extensively to improving the gas detection capabilities of WO₃/WS₂ nanocomposites at room temperature.