A series of polyfluorene copolymers composed of 9,9-dioctylfluorene (DOF) and 2,3-diphenylfumaronitrile (DPFN), poly(DOF-co-DPFN)s, have been synthesized through a palladium (0)-catalyzed Suzuki coupling reaction, and their light-emitting properties have been investigated. The synthesized copolymers were soluble in common organic solvents such as chloroform, toluene, etc and formed a uniform thin film after spin coating. As the contents of 2,3-diphenylfumaronitrile in the copolymers increases, the optical band gaps of the copolymers decreased and HOMO energy levels were also slightly lowered. The absorption and PL emission spectra of the copolymers containing DPFN units shifted to longer wavelength region than those of poly(9,9-dioctylfluorene). Light-emitting devices were fabricated using these polymers as the emissive layers in an ITO/PEDOT:PSS/Polymer/Balq/LiF/Al configuration.