This chapter provides a comprehensive examination of sustainable fibers, highlighting their sources, production techniques, and diverse applications in the textile and materials sectors. It emphasizes the ecological benefits of organically obtained fibers, including cotton, flax, ramie, hemp, and jute, as well as advancements in regenerated fibers such as Ioncell®, Infinna™, and protein-based materials that reflect circular economy concepts. The discourse encompasses bio-based thermoplastic fibers, specifically thermoplastic cellulose and polylactic acid (PLA), as sustainable substitutes for petroleum-derived synthetics. Progress in protein engineering, synthetic biology, and biomimetic spinning is facilitating the scale manufacture of recombinant silk for high-performance uses. These fibers collectively exhibit considerable promise to reduce the environmental effects linked to traditional textiles. Their biodegradability, renewability, and adaptability establish them as essential facilitators of next-generation sustainable materials. The chapter emphasizes the significance of interdisciplinary collaboration and innovation in addressing existing limits and expediting the incorporation of bioinspired fibers across several sectors, including medical, electronics, packaging, and soft robotics.