The increasing demand to substitute petroleum-derived polymers with eco-friendly alternatives has intensified interest in plant-based biopolymers such as cellulose, starch, pectin, lignin, guar gum, and agar due to their biodegradability, renewability, and small ecological footprint. Notwithstanding these benefits, constraints, including inadequate mechanical strength, elevated moisture sensitivity, and low thermal resistance, impede their industrial scalability. This chapter examines the strategic improvement of these biopolymers via the integration of sophisticated nanomaterials, such as nanoclays, nanocellulose, metal nanoparticles, and carbon-based nanomaterials (e.g., graphene oxide, carbon nanotubes). Nanoscale additions boost performance through methods such as uniform dispersion, robust interfacial adhesion, and significant improvement in barrier properties. The chapter explores nanoengineering techniques, including electrospinning, in situ polymerization, and sol–gel synthesis, that enable accurate structural modification and functionalization of biopolymeric matrices. Case studies encompassing food packaging, agriculture, textiles, and biomedical applications demonstrate enhancements in performance. Specifically in food packaging, improved mechanical, barrier, antibacterial, and antioxidant properties have been attained. The chapter discusses regulatory considerations of nanomaterial usage that promote standardized safety frameworks. The integration of nanotechnology with bio-based polymers signifies a pivotal advancement toward achieving circular economy objectives and promoting the development of sustainable, high-performance material systems.