Three-dimensional hierarchical nanostructures with carefully designed constructing units are promising for photocatalysts because of their improved light harvesting capability, enlarged specific surface area, increased active sites, and more rapid charge migration. In this paper, nanostructured thin films of belt-on-belt hierarchical TiO2 were fabricated on metallic Ti substrates for photocatalytic applications. Arrays of anatase TiO2 nanobelts on Ti substrates were firstly achieved by an alkali-hydrothermal approach. A wet-chemistry route based on solution combustion synthesis was then adopted to cover the nanobelt trunk with branches of ultra-thin hydrogen titanate nanobelts, which decomposed to anatase TiO2 upon a subsequent air calcination. When utilized to assist photodegradations of rhodamine B in water under the illumination of a Xe lamp, the hierarchical TiO2 exhibited averagely a 13% increase in the efficiency when compared with the pristine TiO2 nanobelts. The Ni-doping in the branches further improved the photocatalytic activity, which is 1.5 times that of the pristine TiO2 nanobelts. The present belt-on-belt hierarchical TiO2 thin films with carefully controlled compositions and nanostructures are thus of potential interest in photocatalysis.