A series of amine-functionalized poly(9,9-dihexylfluorene) (PFH) derivatives, PFH-NH2F-39-1 (P1), PFH-NH2F-19-1 (P2), PFH-NH2F-9-1 (P3), and PFH-NH2F-17-3 (P4), and PFH-NH2F-4-1 (P5), were developed to form organic/inorganic hybrid composites with CdSc/ZnS nanoparticle for polymeric light-emitting diodes (LEDs). The structures and purities of all desired polymers were fully characterized by H-1 and C-13 NMR, UV-vis and photoluminescent spectroscopy, gel permeation chromatography, elemental analyses. The hybrid nanocomposites were in situ formed through these amino-functionalized polyfluorene derivatives doped with core-shell CdSe/ZnS quantum dots (QDs). The detailed characterizations of their photophysical properties revealed that rapid Forster energy transfer from the conjugatee polymers to the red-emitting QDs afforded an efficient red color emission. The preliminary polymeric LEDs fabrication with the configuration of ITO/DB/nanocompositcs/Al achieved red emission for the ill Situ prepared hybrid nanocomposites. The investigation of device performance indicates that these nanocomposites are promising red light-emitting polymeric LED materials with good performance in providing excellent color purity, stability, and robustness. Such strategy provides us a platform to achieve red-emitting hybrid nanocomposites as the active materials for LEDs.