Increasing emphasis has been placed on the use of renewable resources, on decreased reliance on petroleum in order to better utilize global energy needs. Biological structures available in nature have been a constant inspiration to the design and fabrication of the new line of functional biomaterials whose unique phenomena can be exploited in novel applications. In tissue engineering for example, a natural biomimetic material with close resemblance to the profile features existed in a native extracellular matrix could provide a temporary functional platform to regulate and control cellular interactions at a molecular level and to subsequently direct a tissue regeneration. However, the lack of rigidity of natural materials typically limits their mass production. One promising approach to address this shortcoming is to introduce a biomimetic composite material reinforced by high purity nanofibers found in nature. As an attractive reinforcing filler phase, cellulose nanowhiskers (CNWs) offer exceptional properties such as high aspect ratio, large interface area, and significant mechanical performance. As such, CNWs could integrate a viable nanofibrous porous candidate, resulting in superior structural diversity and functional versatility. Inspired by the fascinating properties of cellulose and its derivatives, we have designed two bio-inspired nanocomposite materials reinforced with CNWs in this work. The successful grafting of CNWs within the host matrix and their tendency to interconnect with one another through strong hydrogen bonding gave rise to the formation of a three-dimensional rigid percolating network, fact which imparted considerable mechanical strength and thermal stability to the entire structure with only a small amount of filler content, i.e. 3 wt.%. Also, the biocompatibility of the nanocomposite was probed by in-vitro incubation of human-bone-marrow-derived mesenchymal stem cells (MSCs), which resulted in the invasion and proliferation of MSCs around the nanocomposite at day 8 of culture. The green functional biomaterial with its unique features in this work could open new perspectives in the self-assembly of nanobiomaterial for tissue-engineered scaffolding, while it could make the design of the next generation of fully green functional biomaterial a reality.