Cellulose, especially cellulose nanocrystal and cellulose nanofibril, has captured much attention as a bio-based candidate for the reinforcement of elastomers, but data in the use of regenerated cellulose (RC) from alkaline-urea-aqueous system as reinforcing agent remain scarce. In this contribution, fully bio-based hybrids were produced by flocculating a mixture of natural rubber (NR) latex and cellulose alkaline urea aqueous solution, during which NR latex particles were demulsificated to form the polymeric matrix while the porous honeycomb-like RC phase was also generated due to the coagulant-induced gelation, indicating that both the matrix and the filler were synchronously in situ formed by the bottom-up route. RC possesses a unique honeycomb-like structure which apparently could induce extensive physical entanglements, making the filler tightly interlocked with the matrix and therefore favoring the stress transfer. Predictably, RC;without any chemical modification, could endow NR with a pronounced reinforcement. Overall, this work provides (0 a unique inspiration for reinforcing NR with honeycomb-like cellulose and (ii) a better understanding of how could RC truly reinforce NR composites.