In this study hybrid ternary polymeric nanocomposites based on carbon nanotubes (CNTs) and graphite nanoplatelets (GNPs) are examined for their enhanced transport properties, over mono-nanofiller composite systems, originated via a synergy mechanism. Using an epoxy as the host matrix, a number of CNTs/epoxy, GNPs/epoxy and hybrid CNTs/GNPs/epoxy specimens are processed and their electrical and thermal properties are characterized. Furthermore, these transport properties are also estimated using a set of recently developed computational models based on percolation analysis and statistical continuum mechanics. Results suggest that the models, in agreement with the experimental observations, confirm the presence of the synergy effect for both the electrical and thermal transport properties. Both the computational and experimental studies suggest incorporating miniscule amount of auxiliary nanofiller (ex. 10%wt CNTs compared to GNPs), boosts the electricalconductivity of the hybrid composites by several orders of magnitudes.Furthermore, the experimental measurements and the strong contrast computational models suggest that, owing to the formation of the hybrid CNT/GNP network, the hybrid CNT/GNP/polymer nanocomposites outperform their single-nanofiller counterpart configurations. The investigation affirms that the particle agglomeration severely affects the transport properties of the hybrid nanocomposites and it is the root cause for the conflicting results in the literature.