Metastable TiO2/Bi4MoO9heterojunctions are synthesized using a hydrothermal method. TiO2nanoparticles, which are used as templates in the hydrothermal process, can induce the heterogeneous nucleation and 1D preferential growth of Bi4MoO9to form TiO2/Bi4MoO9heterojunctions. The TiO2/Bi4MoO9heterojunctions exhibit very efficient visible-light photocatalytic activity, which is much higher than those of TiO2nanoparticles, Bi4MoO9microcubes, and TiO2/Bi2MoO6composites. This could be mainly ascribed to the synergistic effects of the band structure matching and the unique microstructure between TiO2nanoparticles and Bi4MoO9nanobelts in the heterojunctions. The Bi4MoO9nanobelts with ≈150 nm in width promote the production of photogenerated electron–hole pairs due to its narrow bandgap. The TiO2nanoparticles embedded into Bi4MoO9nanobelts still remain small size, large specific surface area, and high crystallinity. These not only facilitate the transfer of photogenerated holes from Bi4MoO9nanobelts to TiO2nanoparticles, but also improve the holes capture rate on the surface of the heterojunctions.