Lightweight and flexible materials with high conductivity and low thickness are highly desirable for electromagnetic interference (EMI) shielding applications. Developing hybrid nanostructured materials, which combine the properties of their constituents, is an excellent strategy to create highly effective EMI shields. In this study, we report a hybrid polymer nanocomposite composed of carbon nanotube (CNT) and ZnO nanowire (ZnONW) for EMI shielding applications. We found that the combination of a conductive filler (CNT) and a dielectric filler (ZnONW) with a similar geometry is an effective method to fabricate nanocomposites with enhanced EMI shielding. We achieved high average shielding effectiveness of 27.3 dB (with a maximum of 41 dB at 10.2 GHz) for a sample of CNT:ZnONW (5.0:2.5 wt%) with only 1.1 mm thickness, which is among the best-reported values in the literature for polymer nanocomposites with similar filler loading and thickness. This performance originates from the excellent electrical conductivity and dielectric properties of hybrid nanocomposites, combined with the geometry of ZnO nanowire. A comparison of the shielding properties of the developed hybrid nanocomposites with the literature implies that they are promising functional materials in the world of EMI shielding applications.