This paper reports the experimental feasibility of using VO2(B) nanomaterial as a high-capacity, high-voltage, and promising performance cathode material for magnesium-ion battery. Recent research on monoclinic VO2(B) material in the prevailing lithium-ion batteries has attracted more and more interest, primarily due to the layered structure and large charge/discharge capacity of the material. We synthesized VO2(B) in both forms of nanorods and nanosheets via a facile hydrothermal method to use as the cathode for an Mg ion battery, and investigated their properties, and electrochemical performance and mechanism with SEM, FT-IR, XRD, XPS, ICP and the electrochemical technique. . An encouraging performance is achieved with VO2(B) in the form of nanorods instead of nanosheets. The VO2(B) nanorods are capable of operation with a high discharge voltage at 2.17 V vs. Mg2+/Mg and a high initial discharge specific capacity of 391 mAh/g at a voltage ranging from −1.00 V to 0.30 V vs. Ag+/Ag, corresponding to 0.61 mol Mg per unit at a current density of 25 mA/g at 20 °C. Even at 12 °C, the first discharge specific capacity of 394 mAh/g is obtained with a capacity retention ratio up to 52.2% after 60 cycles at 50 mA/g, showing a better cyclability and capability. Significantly, the VO2(B) nanorods are confirmed to be a promising cathode material for use in Mg rechargeable batteries of a high capacity and a high voltage.