The authors demonstrate full color tunability in the visible range, including white emission, by polymer nanofibers based on binary blends of conjugated materials. The nanofibers are realized by electrospinning and their emission is based on the dipole-dipole energy transfer from a blue-emitting donor and a red-emitting acceptor conjugated polymer. The fibers are characterized by scanning electron microscopy and time-resolved and cw photoluminescence. Light emission is tuned from blue to red, including bright white with color coordinates (0.38, 0.34) according to the standard of the Commission Internationale de l'Eclairage. Polymer nanofibers based on blends of conjugated compounds turn out to be a promising class of organic semiconductor building blocks for nanophotonics.