Metal oxides, especially the wide‐gap semiconductors, are the most important functional materials and have been widely studied for the use in the areas ranging from photovoltaic/photocatalysis to photo‐/eletrochromics and sensors. Synthesis of metal oxide nanostructures with controlled size and shape is of considerable interest, owing to that the performance of metal oxide‐based devices is largely influenced by the morphology of metal oxide building units, especially in nanometer scale. In this presentation, we will show our recent results on the rational design of the diverse morphologies of the typical metal oxides, like TiO2, ZnO, WO3, etc, with 1D, 2D, or 3D architectures, based on the precise controlling of the starting solutions. Some general mechanisms on the hydrothermal synthesis of metal oxide nanostructures were also proposed. As an example application of these metal oxide nanostructures, the effect of the nanostructure morphology on the performance of dye-sensitized solar cells was studied.