The present work reveals results on the network formation of graphene nanoribbon (GNR) synthesized using a nonoxidative technique from multiwalled carbon nanotube (MWCNT). MWCNT and GNR presented comparable powder conductivity and dispersion state in a poly(vinylidene fluoride) (PVDF) matrix. This enabled us to purely discern the effect of geometrical features of the nanofillers on network formation by comparing the rheological and electrical percolation in the PVDF matrix. Unique features of the rheological response of PVDF/ GNR nanocomposites, such as abrupt transition to a solid state, were interpreted according to a network structure activated by the formation of primary and secondary entanglements between adsorbed and bulk polymer chains. However, MWCNT nano composites presented a rheological behavior consistent with a strongly flocculated network structure formed through the direct tube tube contacts and mechanical entanglements. Poor broadband electrical conductivity of the GNR nanocomposites compared to their MWCNT counterparts confirmed our conclusion from the rheological results.