A sandwich-structured NiMn2O4@reduced graphene oxide (NiMn2O4@rGO) nanocomposite consisting of ultrathin NiMn2O4 sheets uniformly anchored on both sides of a three-dimensional (3D) porous rGO is presented. The NiMn2O4@rGO nanocomposites prepared through a dipping process combining with a hydrothermal method show a good electrochemical performance including a high reversible capability of 1384 mAh g−1 at 1000 mA g−1 over 1620 cycles, and an superior rate performance. Thus, a full cell consisting of a commercial LiCoO2 cathode and the NiMn2O4@rGO anode delivers a stable capacity of about 1046 mAh g−1 (anode basis) after cycling at 50 mA g−1 for 60 times. It is demonstrated that the 3D porous composite structure accommodates the volume change during the Li+ insertion/extraction process and facilitates the rapid transport of ions and electrons. The high performance would enable the presented NiMn2O4@rGO nanocomposite a promising anode candidate for practical applications in Li-ion batteries.