Solvent-resistant nanofluidics is demonstrated as sub-100-nm technology for fabricating organic light-emitting fibers, with superior control over diameter and spatial arrangement. Nanofluidics is carried out with optimal resistance to organic solvents commonly employed to dissolve conjugated polymers. The optically active nanofibers, with diameters around 60 nm, are found to exhibit photoluminescence emission polarized along their axis.