In this work, a novel kind of carboxyl-containing poly(ether ether ketone) (PEEK-COOH) was successfully synthesized and carefully characterized. Based on PEEK-COOH as macromolecular ligands, a series of luminescent rare earth polymer complexes (PEEKn-Eux-Tb1-x) were prepared and made into flexible films. The effects of the ratio of carboxyl ligand to rare earth ions on fluorescence intensity of complexes were studied and discussed. When the molar ratio was 6:1, the fluorescence emission intensity reached a maximum. Furthermore, the relative emission intensity of Tb3+ and Eu3+ binary system depended on their ratio and the intensity of fluorescence emission peak exhibited continuous change. Because of this, the color of the prepared fluorescent films could range from bright green to fire red, and each color has high purity. The fluorescence lifetime of complexes ranged from 0.428 to 0.511 ms. Absolute quantum yield of PEEK-Eu0.4-Tb0.6 was 8.4%. Beside this, these fluorescence films exhibited a high thermal stability with 5 wt. % in the range of 240–250°C, and its tensile strength was about 28 MPa. In addition, PEEKn-Eux-Tb1-x films possessed good optical transparency. All the interesting results suggested the potential application of the luminescent rare earth polymer complexes in display devices and photo-electronic devices.