A facile method using acid leachate of ilmenite as the precursor has been successfully developed to tailor the structure of Fe2O3. The morphology and structure of the final product can be controlled from nanoparticles, microcubes, rhombohedrons to microspheres by varying the synthetic parameters. Detailed characterization showed that the microspheres had a hierarchical structure and was actually consisted of nanoblocks subunits. A possible mechanism was proposed for the formation of the hierarchically structured Fe2O3 microspheres. Due to its large surface area and abundant functional groups, the Fe2O3 microspheres could efficiently remove organic dyes in aqueous solution. The measured maximum adsorption capacities were 723.8, 150.7, and 54.5 mg/g for Congo red, Methyl orange, and Methylene blue, respectively, which were generally higher than those for Fe2O3 with other structures reported in literature. This work provides a novel approach to using waste as the resource for the preparation of low-cost and efficient adsorbent materials.