Developing stable and solution-processable highly conductive polymers has been the research goal in organic electronics since the first demonstration of metallic conductive polyacetylene. Here, we used a unique quinoid-resonant building block thieno[3,4-b]thiophene (TbT) to develop a new water-dispersible conducting polymer, PTbT-Me:PSS. Linear polymerization and large surfactant counterion, poly (styrenesulfonate) (PSS−), were introduced, which enabled a high electrical conductivity of 68 S cm−1 and exhibited water-dispersible property. Interchain bipolaron was found in PTbT-Me:PSS when compared with polaron in PEDOT:PSS in their conducting mechanism. Moreover, we applied this highly conductive PTbT-Me:PSS as the solution-processed polymer thermoelectric material and a decent power factor of 3.1 μW m−1 K−2 was achieved.