Supercapacitors have attracted considerable attention because they can store more energy than conventional capacitors and can have higher power densities than batteries. In this study, microwave irradiation was used for the rapid and facile synthesis of mesoporous RGO@(Co,Mn)3O4 oxide nanosheets as an electrode material for supercapacitor applications. The as-prepared electrode exhibited a high capacitance of 1004Fg−1 at 3mVs−1 in a 6M KOH electrolyte solution. Moreover, the electrode showed good specific retention and high Coulombic efficiency of 81.6% and 96.9%, respectively, after 3000 charge-discharge cycles. The electrode also exhibited a high energy density of 53Whkg−1 (at power density of 500Wkg−1) and high power density 5000Wkg−1 (at energy density of 27Whkg−1). Overall, the RGO@(Co,Mn)3O4 electrode showed very promising results for supercapacitor applications.