A new derivative (EDOS-POSS) of 3,4-ethylenedioxyselenophene integrated with alkyl-substituted polyhedral oligomeric silsesquioxane (POSS) cage was synthesized and characterized. The electroactive monomer was successfully polymerized via both chemical and electrochemical methods. The obtained polymer called PEDOS-POSS was solution-processable and soluble in common organic solvents like tetrahydrofuran, toluene, dichloromethane, and chloroform. PEDOS-POSS polymer exhibited electrochromic behavior: pure blue when neutralized and highly transparent when oxidized. When compared to the parent PEDOS (1.40 eV with lambda(max) = 673 nm), PEDOS-POSS polymer film has a somewhat higher band gap (1.50 eV with lambda(max) = 668 and 724 nm). Also, PEDOS POSS exhibited high optical contrast ratio (59%) and coloration efficiency (593 cm(2)/C for 95% switching) with a low switching time (0.7 s) due to the presence of POSS cage in the polymer backbone. In addition, PEDOS-POSS polymer film was highly robust and stable under ambient conditions (without purging the electrolyte solution with inert gas). Polymer films demonstrated high electrochemical stability; for example, it retained 76% of its electroactivity after 5000 cycles. Furthermore, the polymers exhibited fluorescent properties and exhibited a reddish orange emission centered about at 640 nm. Based on the findings, to the best of our knowledge, it can be concluded that the polymers are the first examples of soluble and fluorescent PEDOS derivatives. These promising properties make PEDOS-POSS polymer a potential material for bioapplications like imaging the cancer cells as well as optoelectronic applications.