High electrical conductivity and high Seebeck coefficient are the two important prerequisites for achieving high power factor in organic thermoelectric (TE) materials. However, these two properties are quite often in conflict. In this work, we demonstrate that incorporating CNT in a conducting polymer PEDOT:PSS could facilitate the formation of stable and effective conductive channels, which provides an effective approach to optimize the TE parameters with simultaneously enhanced electrical conductivity and Seebeck coefficient against the initial organic TE materials. With further tailoring charge concentration of the SWNT/PEDOT:PSS composite by base treatment, the TE performance could be improved. Nanocomposite of 60 wt% SWNT and PEDOT:PSS exhibits high TE power factor of ∼526 μW m−1 K−2 with Seebeck coefficient of 55.6 μV K−1 and electrical conductivity of 1701 S cm−1, which is by far one of the highest power factors among the reported organic TE nanocomposites. Considering thermal conductivity around 0.4–0.6 W/m K, the highest estimated ZT value of our TE nanocomposite can approach 0.39, demonstrating the feasibility of this strategy to enhance TE performance of organic composite materials. Display omitted