Advances in renewable nanomaterials provide new pathways for designing soft and solid systems with adaptive, responsive, and multifunctional properties. Drawing from colloidal science, we report a suite of material platforms built from nanopolysaccharides that leverage interfacial assembly and dynamic structuring to achieve programmable behavior across applications that include biomedical, environmental, and optoelectronic fields.  We first demonstrate how magnetic nanoparticles adsorbed to cellulose nanofibers induce rapid and reversible alignment in hydrogels, enabling magnetoresponsive control over light reflection and optical encoding for information storage (1).  Building on the role of anisotropic nanofibers, we design injectable hydrogels that mimic natural regeneration mechanisms. These composites—comprising dopamine-modified chitin and cellulose nanofibers—deliver antioxidants and antibacterial agents in response to wound microenvironments, achieving complete skin regeneration in vivo (2). Renewable nanofibers further enhance structural adhesives, forming high-strength, water-resistant complexes through hydrogen bonding. These sustainable adhesives exhibit bonding strength surpassing 20 MPa, rivaling commercial products while avoiding organic solvents (3).  At larger scales, the nanofibers stabilize bicontinuous emulsions at ultra-low concentrations to form macroporous cryogels with dual-scale porosity and mechanical robustness (4). We extend this templating approach to graphene oxide assemblies at oil–water interfaces, generating ultralight aerogels with tubular, conductive morphologies. These structures offer hierarchical design freedom for applications such as EMI shielding and flexible electronics (5).  For environmental uses, we integrate MOFs and nanocellulose into ambient-dried aerogels capable of harvesting atmospheric water and sustaining plant microclimates via solar-driven release (6).  Finally, liquid-in-liquid printing in aqueous suspensions enables free-form fabrication of conductive, volumetric threads, including core–shell filaments with mechanical robustness and programmability (7).  Together, these studies demonstrate how nature-inspired structuring of renewable nanomaterials via interfacial assembly can yield intelligent systems with broad functionality and sustainability.