The lithium storage performance of silicon (Si) is improved substantially by forming composite of nano-Si particles embedded homogeneously in graphene nanosheets (GNs) using a simple discharge plasma assisted milling (P-milling) method. The synergistic effect of the rapid heating of the plasma and the mechanical ball mill grinding with nano-Si as nanomiller converted the graphite powder to GNs with the integration of nano-Si particles in the in-situ formed GNs. This composite structure inhibits the agglomeration of nano-Si and improves electronic conductivity. The cycling stability and rate capability are enhanced, with a stable reversible capacity of 976 mAhg−1 at 50 mAg−1 for the P-milled 20 h nano-Si/GNs composite. A full cell containing a commercial LiMn2O4 cathode is assembled and demonstrated a satisfying utilization of the P-milled nano-Si/GNs composite anode with stable working potential. This composite shows promise for application in lithium ion batteries.