Abstract This work focuses on the rheological properties and morphological features, assessed by Atomic Force Microscopy (AFM), of epoxy composites loaded with two very similar graphene-based nanoplatelets, i.e. GNP56 and GNP60, differing fundamentally for the exfoliation degree (56% and 60%, respectively) and consequently for the concentration of carboxylated groups on the nanoparticle edges. The incorporation of the GNP56 and GNP60 nanostructures inside the epoxy matrix considerably changes the rheological response of the nanofilled resin. The viscoelastic behavior shown by the graphene-based samples perfectly correlates with the different morphology of the two nanofillers that is congruent with the difference in the exfoliation degree percentage.