Polymeric materials reinforced with nanofillers continue to fulfill the worldwide demand for alternative materials with low cost and better physico-mechanical properties. These materials are prepared by mixing polymers with nanofillers (e.g. layered silicates, metal oxides, carbon nanotubes (CNTs) and graphene) using in situ or melt blending techniques for improved physico-mechanical properties. Among all the nanofillers, CNTs and graphene have emerged as subjects of tremendous scientific interest and have attracted a great deal of attention from across several disciplines in recent years. Among the nanofillers, graphene has shown very good electrical, thermal, mechanical and gas barrier properties in combination with polyolefins. The present review is an overview of polyolefin/graphene based composites, especially of polypropylene (PP) and polyethylene (PE), with special emphasis on their methods of preparation, properties and potential applications.