As-anodized amorphous TiO₂ nanotube arrays (TNAs) are immersed in hot ammonia solution (90 °C), which can both spontaneously reconstruct the amorphous TNAs to be anatase nanoworm/nanotube hierarchical structures in situ and simultaneously implant nitrogen into them. These hierarchical structures, having larger surface area, higher electrical conductivity and broader light absorption range than the original TNAs, possess dramatically enhanced photocatalytic activity for degradation of methyl orange (MO) under visible light irradiation. The optimized nitrogen doped hierarchical structures exhibit a best photodegradation rate (K) of 0.722 h⁻¹, which greatly exceeds the degradation rate of the original TNAs annealed in ambient air at 500 °C for 2.5 h. This simple technique would enable us conveniently to design and fabricate highly photoactive one-dimensional TNAs-based functional materials applicable to photocatalysis and solar energy conversion.