This Letter presents the fabrication and characterization of a perylene (Per) and Rhodamine 6 G (Rh 6 G) co-doped polymeric fiber. The spectroscopic properties (luminescence spectra, attenuation, energy transfer) of the co-doped polymethyl methacrylate (PMMA) fiber are presented. Two different concentrations of Rh 6 G (2.2×10 4 and 4.1×10 4mol/L) and a constant Per concentration (6.2×10 4mol/L) are used in the experiments. The luminescence spectrum changes versus the fiber length are discussed. Additionally, the ratio of the maximum fluorescence peaks of the used dyes is calculated versus the fiber length. The obtained results show the energy transfer from Per (donor) to Rh 6 G (acceptor). The proposed co-doped fiber can be used in applications in lighting and sensor technology.