Mixed transition-metal oxides (MTMOs) are regarded as advanced electrode materials for sodium-ion batteries (SIBs). In this study, amorphous CoSnO3 nanocubes wrapped by reduced graphene oxide (marked as a-CoSnO3@rGO) are successfully designed via a facile solvothermal method accompanied by a simple calcination process. To examine this design, sodium storage behaviors of a-CoSnO3@rGO nanocomposites are investigated in detail. Compared with the pristine a-CoSnO3, a-CoSnO3@rGO nanocomposite with 25.1 wt% rGO exhibits enhanced electrochemical performance, for instance, it delivers a high specific capacity of 229.9 mAh g−1 after 100 cycles at 50 mA g−1 with a Coulombic efficiency close to 99%, and it is capable of maintaining a specific capacity of 205.7 mAh g−1 even at a high current density of 800 mA g−1. Superior electrochemical performance of a-CoSnO3@rGO is primarily attributed to intrinsic “self-matrices”, rGO-wrapping network, and crystalline texture engineering. Indeed, the unique 3D-rGO-wrapping architecture of a-CoSnO3@rGO manifests compelling advantages, such as developing a high conductive three-dimensional network, facilitating the ion/electron diffusion, accommodating volume change, and strengthening interaction between rGO and a-CoSnO3. It is believed that the proposed strategy may provide new insights to design hybrid anode nano-materials for advanced SIBs.