Transition metal oxides have been extensively studied as anode materials for lithium ion batteries due to their high capacity. However, the intrinsically low electronic conductivity and large volume changes upon repeated cycles are the obstacles for obtaining their high electrochemical properties. In this work, we report the novel construction of uniform Ni/MnO porous microspheres by an in situ conversion from their solvothermally synthesized precursor composites (xNiCO3·yMnCO3). The structures of the precursor composites can be controlled by the solvothermal duration and solution compositions. During the high-temperature annealing process, the precursor composites were transferred into Ni and MnO composite and porous structure was created by the decomposition of the carbonate materials. As an anode material for lithium-ion battery, the porous Ni/MnO electrode demonstrates high reversible capacity of 700.6 mA h g−1 after 250 cycles. Moreover, the Ni/MnO microspheres exhibit excellent rate capacity. The exceptional electrochemical performances are attributed to the homogeneous distribution of nickel nanoparticles within the MnO microspheres and porous structures throughout the whole microspheres, which can improve the electronic conductivity of the electrode materials and keep the structural integrity upon repeated cycles.