This study discloses, for the first time, the impact of Graphene Oxide (GO) chemical reduction on structure and performance of a Polyethylene (PE) rich biphasic system, with Polypropylene (PP) representing the morphology tunable micro phase. A 2% weight fraction of the interface modifier Reduced Graphene Oxide (RGO), together with a strategic mixing of the components, led to RGO high exfoliation and selective localization at the PE/PP interface, demonstrated by Transmission Electron Microscopy (TEM). This resulted into an extremely fine morphology for the ternary system PE/PP/RGO, with micro phase having a uniform droplet diameter distribution, proven by Scanning Electron Microscopy (SEM). The material had greater stiffness, toughness, storage and loss modulus than those of virgin PP, with strength being similar to the one of neat PP. This study provides industrial sectors, such as transportation and energy, with the potential to replace PP rich products with those made of a cheaper, simpler, yet performant PE.