A new technique to fabricate ultrathin colorful fibers has been developed via ultraviolet (UV)-assisted solventless electrospinning. The precursor solution contains UV curable polyurethane acrylate (PUA) and colorful UV gel nail polish, and can be electrospun into ultrathin fibers without solvent evaporation in the atmosphere of nitrogen, owing to rapid curing of the acrylate bonds in the spinning jet under the radiation of UV light. The resulting fibers have good color fastness and high stretchability (more than 140%). In addition, various fiber colors can be conveniently adjusted and obtained through formulating the recipe of the precursor solution. Compared to the traditional dyeing process, this method is ecofriendly and promising to prepare colorful fibers, which may be used in textiles, clothing, and anticorrosive coatings.