Wool fibers are treated with titanate tetrabutyl in the presence of C. I. Reactive Blue 69 dye in a one-pot process under hydrothermal conditions. The fiber structure and as-prepared particles are characterized. The properties of percentage of exhaustion, K/S value, color fastness to light, tension, photocatalytic activity, and diffuse reflectance spectrum are investigated. The experimental results indicate that after treatment the wool fiber surfaces are evenly immobilized with a thin layer of anatase phase TiO2 nanoparticles. The TiO2 nanocrystals are grafted onto wool fibers via the C-Ti4+, S-Ti4+(Ti2+), and N-Ti4+ bonds. The thermal stability of wool fibers changes a little. The capability of wool fibers to protect against ultraviolet radiation is improved. The tensile properties decrease. The photocatalytic activity to decolorize methylene blue dye is endowed. A high degree of percentage of exhaustion and high K/S value are obtained by adding a certain amount of acetic acid in the precursor solution.