Monoclinic BiVO 4 (m-BiVO 4 ) micro/nanostructures, such as nanorods, nanofibers, bundle-like nanostructures, and porous submicrometer-sized rods, have been successfully synthesized by a facile solvothermal method in an ethylene glycol–water–sodium oleate system. The morphologies and sizes of m-BiVO 4 micro/nanostructures can be controlled by adjusting the synthetic parameters, such as the concentrations of sodium oleate and reaction time. Among them, the synthesized m-BiVO 4 nanorods have rectangular cross sections, and can grow along the [001] direction, and are enclosed by well-defined facets, such as (002), (240), and (2¯ 1 0), which are distinct from that with circular cross sections. A crystallization-cleavage-disassembly process has been proposed for the formation of m-BiVO 4 nanorods with rectangular cross sections. The photocatalytic activity of m-BiVO 4 nanostructures is affected greatly by the sizes and shapes of m-BiVO 4 nanostructures. Photocatalytic measurements show that the m-BiVO 4 nanorods with rectangular cross sections exhibit higher photocatalytic activities of Rhodamine B in comparison with m-BiVO 4 nanofibers with circular cross-sections and porous submicrometer-sized rods.