In this work, we present a simple two-step method to fabricate a series of three-dimensional (3D) interconnected networks of ultrathin mesoporous Ni-Mo oxide nanosheet arrays with enhanced electrochemical properties. The optimized Ni-Mo oxide nanosheets directly grown on Ni foam can deliver a high specific capacitance of 1189F/g at a current density of 1A/g, which is substantially higher than that of pure NiO nanosheets (191F/g at 1A/g). Moreover, the ternary Ni-Mo oxide nanosheets exhibit a good rate capability and remarkable long-term cycling stability (77.7%) over 5000 cycles at 5A/g. Our work suggests that the resulting products prepared by this scalable and cost-effective fabrication process are very suitable and promising as advanced electrode materials for high-performance supercapacitors.