Mesoporous metal oxides (MOs) have attracted significant interest in heterogeneous catalysis due to their wide pore size distribution and high pore volume. Herein, we present a facile mechanochemical nanocasting strategy using aluminum hydroxide as the mesoporous structure-directing agent, which overcomes the drawbacks associated with wet template-assisted methods. In this procedure, by simply grinding a mixture of commercial aluminum hydroxide and MO precursors, a series of mesoporous MOs with high specific surface areas and narrow pore size distributions have been constructed in a short time (e.g., Fe₂O₃, 280 m² g⁻¹; Co₃O₄, 155 m² g⁻¹; CeO₂, 192 m² g⁻¹; ZrO₂, 170 m² g⁻¹; CuO_x–CeO_y, 177 m² g⁻¹; FeO_x–CeO_y, 170 m² g⁻¹; CoO_x–CuO_y–CeO_z, 154 m² g⁻¹; CoO_x–FeO_y–CeO_z, 133 m² g⁻¹). It is expected that this strategy may open up new opportunities for fabricating a number of advanced porous materials with abundant porosity in the near future.