A novel efficient antenna complex of Eu3+ [Eu(CPFHP)3(DDXPO)] supported by a highly fluorinated carbazole-substituted β-diketonate ligand, namely, 1-(9H-carbazol-2-yl)-4,4,5,5,5-pentafluoro-3-hydroxypent-2-en-1-one (CPFHP) and the 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene oxide (DDXPO) ancillary ligand, has been synthesized, structurally characterized, and its photoluminescent behavior examined. The single-crystal X-ray diffraction analysis of Eu(CPFHP)3(DDXPO) revealed that this complex is mononuclear, and that the central Eu3+ ion is surrounded by eight oxygen atoms, six of which are provided by the three bidentate β-diketonate ligands. The remaining two oxygen atoms are furnished by the chelating phosphine oxide ligand. The coordination polyhedron is best described as that of a distorted square antiprism. The photophysical properties of Eu(CPFHP)3(DDXPO) benefit from adequate protection of the metal by the ligands with respect to non-radiative deactivation as well as an efficient ligand-to-metal energy transfer process which exceeds 66% in chloroform solution with a quantum yield of 47%. As an integral part of this work, the synthesis, characterization, and luminescent properties of poly(methyl methacrylate) (PMMA) polymer films doped with Eu(CPFHP)3(DDXPO) are also reported. The luminescent efficiencies of the doped films (photoluminescence quantum yields 79−84%) are dramatically enhanced in comparison with that of the precursor complex. The new luminescent PMMA-doped Eu(CPFHP)3(DDXPO) complex therefore shows considerable promise for polymer light-emitting diode and active polymer optical fiber applications.