The fabrication of plant-based biopolymer-reinforced fibres has emerged as a sustainable alternative to conventional synthetic composites, addressing numerous environmental concerns such as plastic pollution and carbon emissions. Derived from renewable resources, biopolymers including cellulose, lignin, starch, pectin, and polyhydroxyalkanoates, in combination with natural fibres like jute, flax, hemp, and coir, offer high degree of biodegradability, biocompatibility, and functional tunability. This chapter provides a thorough summary of their classifications, surface and mechanical properties, and the function of mechanical interlocking, hydrogen bonding, and fiber–matrix interactions in reinforcing processes. Various fabrication methods such as compression moulding, extrusion, injection moulding, solvent casting, electrospinning, and advanced approaches like 3D printing, in situ polymerisation, and hybrid layering are critically examined, with a focus on scalability, interfacial compactibility, and structural performance. This approach has a wide application in automotive, marine, aerospace, construction, biomedical, and packaging sectors, demonstrates their flexibility, while difficulties such as moisture sensitivity, thermal instability, and interfacial incompactibility are addressed. The section also delves in to next-generation materials, such as nanocellulose, and lignin-based bionanocomposites, emphasising their potential for smart, multifunctional applications likewise it also identifies natural fiber-reinforced biopolymer composites as a key contributors to circular economics and green technologies, supporting ecologically benign, cost-effective, and long-lasting material solutions.