Nanosphere assembled mesoporous TiO2 products with large specific surface area and high crystallinity were prepared by a combined hydrothermal and post-heating process, where absorbent cotton was used as a template. The as-synthesized samples were characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, N-2 adsorption/desorption, Fourier transform infrared spectroscopy, and UV-Vis diffuse reflectance spectroscopy. Results indicate that the obtained products exhibit a unique 3D mesoporous structure and demonstrate a significantly improved photocatalytic performance, which can be attributed to concurrent effects of high surface area, the presence of accessible mesopores channels and high crystallinity.