Recently, graphene has played a promising role due to its exceptional mechanical and thermal properties and the broad range of applications. This paper reviews the synthesis of graphene and its use as fillers in polymer nanocomposites. The nanocomposites prepared by different methods have the wide range of applications, such as in energy storage devices, biosensor applications, automotive industries and electronic industries. Graphene can be prepared by different methods, for example, mechanical exfoliation, chemical exfoliation, electrochemical exfoliation and Intercalation compound exfoliation. The electrochemical method is environmentally friendly, however, the chemical exfoliation method is cost effective and suitable for commercial production of graphene. In oxidation-reduction method, the oxidation of graphite starts at point’s defects and the temperature has great effects on oxidation of graphite, at low-temperature oxidation is sensitive to impurities and at high-temperature oxidation increases with increasing temperature. Graphene can be incorporated into the polymer matrix by different approaches, such as in situ polymerization, solution, costing method, electrodeposition, and click chemistry method.