Sustainable functional materials derived from renewable biomass provide momentum for the communities of polymer science. We report a supramolecular approach to the preparation of strong biobased polymer nanocomposites with stimuli-responsive behaviors using soybean oil (SO) and cellulose nanocrystals (CNCs). SO-derived polymers were modified with hydroxyl -OH and carboxyl -COOH groups via thiol-ene click chemistry, facilitating hydrogen-bonding interactions with CNCs to improve the overall compatibility in the nanocomposites. These nanocomposites exhibited high tensile strength and maintained high storage modulus up to 200 degrees C. Moreover, these nanocomposites showed a fast and reversible mechanical response to water, an external stimulus to tune intermolecular hydrogen bonding.