A wavelength-converting polymer, a method for fabricating the same and a wavelength-converting device employing the same are provided. The wavelength-converting polymer has a chemical structure represented by formula (I): In formula (I), B and D are the same or different and independently include hydrogen, C1-8 alkyl group, C1-8 alkoxy group, aryloxy group, carboxyl group, —COOK, —COONa or —NH2, or B and D are connected to form a heteroaromatic ring, wherein Z is hydrogen, C1-8 alkyl group, cycloalkyl group or aryloxy group, X1-X4 are the same or different and independently include hydrogen, halogen, C1-8 alkyl group or C1-8 alkoxy group, R is C1-8 alkyl group with or without substitution, and n is an integer of 5 to 1,000.