In this work, hierarchical peony-like FeCO₃ structures of 3–5 μm diameter assembled from nanosheet layers were successfully prepared through a facile and well controlled hydrothermal method in the presence of an anionic surfactant sodium dodecyl sulfate (SDS). The factors influencing the morphology of the hierarchical FeCO₃ structures were investigated. Hierarchical peony-like α-Fe₂O₃ structures assembled from nanoparticles were also fabricated by a thermal treatment of the as-obtained FeCO₃ at 700 °C for 3 h in air. Tested as anode materials of Li-ion batteries, the hierarchical porous peony-like α-Fe₂O₃ structures exhibited an excellent reversible capacity of 1721 mA h g⁻¹ at a current density of 50 mA g⁻¹ and a high cyclic stability at 100 mA h g⁻¹ over 30 cycles. These results demonstrate the hierarchical porous α-Fe₂O₃ is a promising anode candidate for lithium ion batteries.