Fabrication and characterizations of a flexible NO<sub>2</sub> sensor based on tungsten trioxide nanoparticles-loaded multi-walled carbon nanotubes-reduced graphene oxide hybrid (WO<sub>3</sub> NPs-loaded MWCNTs-RGO) on a polyimide/polyethylene terephthalate (PI/PET) substrate have been investigated. A viscous gel of the hybrid materials (WO<sub>3</sub>-MWCNTs-RGO) was prepared with the assistance of α-terpineol. To observe the physical and crystalline properties of hybrid materials FESEM, TEM and XRD was carried-out. Afterwards, sensor was fabricated by drop casting hybrid solution between two fingers gold (Au) electrodes. Finally, gas sensing properties were taken out in open air environment. The sensor showed excellent sensing performance towards NO<sub>2</sub> including a maximum response of 17% (to 5 ppm), a limit of detection (LOD) of 1 ppm, and relatively short response/recovery time (7/15 min). The sensing behaviors of the fabricated flexible sensor were evaluated systematically at different curvature angles (0-90°) and after several times bending and relaxing (0-10<sup>7</sup>). The sensor exhibited excellent mechanical flexibility and sensing properties at room temperature without any significant performance degradation even at a curvature angle of 90° and after 10<sup>6</sup> times bending and relaxing process. The results indicates that economical, light weight and mechanical robustness of the proposed WO<sub>3</sub> NPs-MWCNTs- RGO hybrid based sensor can be a promising building block for the development of high performance flexible NO<sub>2</sub> sensors.