A series of novel human-made functional fibers (biofibers) based on chitin and chitosan are prepared by the wet-spinning and the post chemical modification of chitosan fiber. The wet-spinning gives rise to a series of biofibers: chitin, chitosan, chitin-cellulose, chitosan-cellulose, chitin-silk fibroin, chitin-glycosaminoglycans, chitin-cellulose-silk fibroin, chitosan-tropocollagen, and chitin-cellulose-silk fibroin. The post chemical modification of chitosan fiber gives rise to a series of chemically modified fibers: N-acylchitosans, N-arylidene- and N-alkylidene-chitosans, N-acetylchitosan (chitin)-tropocollagen, and chitosan-transition metal complexes. Some of the current and potential applications of these biofibers are described.