The extraordinary properties of graphene nanosheets (GNS) and the high performance of polymer-based composites have stimulated extensive research in the realm of polymer nanocomposites. This work examines the mechanisms and approach for the production of GNS polymer composites by first principle ab initio calculations. The results show that GNS functionalized with anionic/cationic moieties can initiate anionic/cationic polymerization reactions, leading to chemically bonded GNS polymer composites via the established anionic/cationic polymerization schemes. These outcomes deliver a solid theoretical basis for fabricating strong polymer nanocomposites.