Bi2Te3 based alloy nanosheet (NS)/poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) composite films were prepared separately by spin coating and drop casting techniques. The drop cast composite film containing 4.10 wt % Bi2Te3 based alloy NSs showed electrical conductivity as high as 1295.21 S/cm, which is higher than that (753.8 S/cm) of a dimethyl sulfoxide doped PEDOT:PSS film prepared under the same condition and that (850–1250 S/cm) of the Bi2Te3 based alloy bulk material. The composite film also showed a very high power factor value, ∼32.26 μWm–1 K–2. With the content of Bi2Te3 based alloy NSs increasing from 0 to 4.10 wt %, the electrical conductivity and Seebeck coefficient of the composite films increase simultaneously.