This study reports on MoO3 nanobelts as electrode material for high-performance supercapacitors. We find MoO3 nanobelts electrode exhibits a higher specific capacitance than MoO3 microrods electrode. Thus, an asymmetric supercapacitor utilizing the as-prepared MoO3 nanobelts as the positive electrode material and the carbon nanosheets as the negative electrode material achieves an impressive performance with an energy density of 25.69 Wh kg(-1) at a power density of 1482.25 W kg(-1). We further reveal that the exposed (010) facets in the crystalline MoO3 nanobelts might mainly contribute to its electrochemical performance.