Poly [2,7-(9-oxo-9-phosphafluorenylene)-alt-co-(1,4-aryl-ene)]s, readily prepared from 2,7-dibromo-9-oxo-9-phosphafluorenes and arylene bisboronates, behaved as extended pi-conjugated polymers in the UV-vis absorption spectroscopy and displayed green-blue fluorescence with high quantum yields. Cyclic voltammetry revealed the polymers exhibited electrochromic behaviors and afforded a bandgap of ca. 2.8 eV, consistent with the value from the absorption edge.