The first use of electrospun nanofibrous membranes as highly responsive fluorescence quenching-based optical sensors for metal ions (Fe3+ and Hg2+) and 2,4-dinitrotoluene (DNT) is reported. A fluorescent polymer, poly(acrylic acid)-poly(pyrene methanol) (PAA-PM), was used as a sensing material. Optical chemical sensors were fabricated by electrospinning PAA-PM and thermally cross-linkable polyurethane latex mixture solutions, These sensors showed high sensitivities due to the high surface area-to-volume ratio of the nanofibrous membrane structures.