Developing novel nanostructured anode materials for Mg storage plays an important role in improving the performance of magnesium-ion (Mg-ion) batteries. Two-dimensional (2D) metal borides (MBenes) are evaluated as potential anode materials in the present study. Simulation results demonstrate that Cr2B2 is a competitive anode material, which can deliver a maximum theoretical capacity of 853.4 mAh g−1 with an average open-circuit potential of 0.68 eV vs. Mg2+/Mg. In addition, Cr2B2 as anode also can exhibit superior kinetics due to the low diffusion barrier of 0.38 eV. Comparing with Cr2B2, Mo2B2 exhibits less but still high Mg storage capacity, with a maximum capacity of 502.1 mAh g−1. In addition, Mg diffusion barrier on Mo2B2 is 0.84 eV and the average open-circuit potential is 0.84 V vs. Mg2+/Mg, both of which are still comparable to the reported anode materials for Mg-ion batteries.