Graphene and their derivatives exhibit interesting properties (mechanical properties, electrical and thermal conductivities). When incorporated into polymer matrices, many applications are possible in fields like electronics, medicine, transportation. The goal of the present review is to highlight how graphene can influence the electrical properties of polymer nanocomposites. The first part explains the peculiar structure of graphene, the main ways to synthesize graphene and the influence on electrical conductivity. In this first part, it is also explained how orientation and alignment of graphene platelets or the presence of a second filler can influence the percolation threshold or electrical conductivity of a monophase polymer nanocomposite. Finally, in this first part, we present some generalities on the enhancement of electrical properties by chemical treatments performed on the graphene. The aim of the second part of this review is to show the effect of the incorporation of graphene into immiscible polymer blends on the microstructures and on the electrical properties. Especially, we focus on the concept of selective localization of nanoparticles into a blend: how to predict the localization of graphene and how to tailor the localization by chemical and kinetics factors. Several graphs were drawn, based on the data of 73 publications, to exhibit the influence of different parameters on the electrical conductivity (in S.cm−1) of graphene based polymer blend nanocomposites. Finally, the last part of this review is dedicated to the electrical applications of graphene-based polymer blend nanocomposites.