Get the full paper here: Adv. Mater. 23, 2924 (2011) Renewable high-performance macroscopic functional fibers are prepared by a simple wet-extrusion and coagulation process of hydrogels of native cellulose nanofibrils. The fibers are functionalized to be transparent, conducting, or magnetic and they can host and release guests as payloads. These biobased macrofibers provide a sustainable approach for high-performance and functional fiber technology in 21st century technologies.