Flower-like LiMnPO₄ nanostructures self-assembled with (010) nanosheets were successfully synthesized via a simple hydrothermal method by employing MnSO₄ and Li₂SO₄ as raw materials and an EG–H₂O mixture as the reaction medium solvent. The flower-like LiMnPO₄ nanostructures were characterized by X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy (TEM) and high-resolution TEM. The primary LiMnPO₄ nanosheets are about 30 nm in thickness and dominated by (010) facets. In order to understand the formation mechanism of the flower-like LiMnPO₄ nanostructures, a series of time-dependent experiments were adopted. Based on the experimental results, a possible mechanism was proposed for the formation of LiMnPO₄ nanosheets and the assembly of the flower-like nanostructures. Additionally, the electrochemical performance of the flower-like LiMnPO₄ nanostructures as cathode materials in Li-ion batteries was also investigated by charge–discharge measurements.