We present a joint experimental/theoretical study on the effects of fluorination on structural, electronic, and optical properties of poly[(9,9-di-n-octylfluoren-2,7-diyl)-alt-tetrafluoro-p-phenylene] (PFTFP), a polyfluorene (PFO)-derived conjugated polymer. The combination of optical (UV-vis) and electrochemical (cyclic voltammetry) techniques with atomistic simulations demonstrates an improved oxidative stability of the fluorinated compound with respect to standard PFO. The resulting excellent luminescence efficiency along with the preservation of the good charge mobility, characteristic of the pristine PFO, make PFTFP a superior material for optoelectronic applications in the deep-blue. The comparison with auxiliary model systems provides a microscopic identification of the peculiar effects of fluorine on the structural and electronic properties of the polymer.