Herein, we propose a practical way for direct preparation of gallium oxide nanosheets/reduced graphene oxide (Ga2O3 NSs/rGO) nanocomposites via oxygenic groups contained hydrophilic graphene oxide (GO) template with subsequent annealing treatment. Benefiting from the two-dimensional (2D) nanoarchitecture of Ga2O3 NSs and rGO, Ga2O3 NSs/rGO nanocomposites exhibit enhanced kinetics and improved cycling stability in Li-ion and Na-ion batteries (LIBs/SIBs). The pseudocapacitance performance is authenticated through kinetic analysis. Ex situ XRD and XPS measurements prove that the reversible Li-ion storage in Ga2O3 NSs/rGO electrodes is a conversion reaction and alloying mechanism. In addition, the full cells fabricated by coupling Ga2O3 NSs/rGO anode and LiFePO4/C or Na3V2(PO4)3/C cathodes exhibit outstanding electrochemical performances. In general, such a new approach, which is not specific to Ga2O3 NSs/rGO nanocomposites, offers great opportunities for 2D oxide nanomaterials or nanocomposites as high-perfo...