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We report the facile synthesis and the chemoresistive performances of villi-like WO₃ nanostructures (VLWNs) which were fabricated by RF sputter with glancing angle deposition (GAD) mode. A fast deposition of GAD effectively forms self-assembled anisotropic nanostructures with high porosity and surface-to-volume ratio. The sensing tests were examined for NO₂ detection in dry air and a mixture of reducing gases. As a result, these sensors at 200 °C exhibit an highly selective and sensitive NO₂ detection down to 800 parts per trillion (ppt) level, and could also respond well to NO₂ in the concentration range of 0.2–1 parts per million (ppm) without the interference of gas mixture. These results show that the enhanced sensing properties to NO₂ are attributed to the highly efficient surface modulation by double potential barriers at nano-necks of WO₃ nanostructures.