Conducive nanoparticles (NPs) were proposed to locally amplify the external electric field (EF) intensity at the cell surface to improve cell electroporation. To better understand the physical mechanisms behind this improvement, different types of NPs and several incubation conditions were applied to adherent cells in the present study. The enhancement of electroporation was observed in the presence of conductive NPs but not when non-conductive NPs were used. Experimental data demonstrate the influence of the incubation conditions between cells and NPs, which impact on the number and quality (aggregated or isolated) of the NPs surrounding the cells. While NPs can increase the number of electroporated cells, they have a more pronounced impact on the level permeabilization of each individual cell. Our results reveal the potential of conductive NPs to enhance the efficiency of electroporation via the amplification of the local EF at the cell surface as shown by numerical simulations.