In this study, cellulose nanofiber (CNF)-reinforced poly (lactic acid) (PLA) bionanocomposites were manufactured through industrially scalable equipments. The compatibility differences between hydrophobic PLA and hydrophilic CNF was counteracted using a water-based polyethylene glycol (PEG)/CNF masterbatch approach, hence minimizing CNF self-agglomeration during drying. Polarized light microscopy showed a progressive refinement of the CNF distribution into PLA upon increasing the PEG content. Rheological experiments provided further evidences about the efficiency of the PEG carrier sytem. Indeed the formation of strong CNF interactions or a three-dimensional CNF network was highlighted for the masterbatch-based composites holding 20 wt.% of PEG, corroborating the successfulness of our sustainable approach to disperse effectively CNF through melt blending techniques. Under thermo-mechanical loading, the rigid percolated CNF structure mastered the viscoelastic response of the plasticized composites, demonstrating the load-bearing capacity of well-entangled CNF in the glassy as well as in the rubbery state. This rapid and straightforward physical method is a suitable approach for preparing dried and concentrated melt-processable CNF masterbatches that can be adopted in conventional melt-processing methods at an industrial scale.