This study presents an innovative triple post-treatment method for optimizing the thermoelectric performance of wet-spun PEDOT:PSS fibers. The method involves sequential treatments with sulfuric acid (H₂SO₄), sodium borohydride (NaBH₄), and 1-ethyl-3-methylimidazolium dichloroacetate (EMIM:DCA) in methanol. The optimized fibers exhibit a high power factor of (55.4±1.8) μW m⁻¹ K⁻² at 25°C and an output power density of (60.18±2.79) nW cm⁻² at a temperature difference of 10 K. The treatments effectively remove excess insulating PSS, enhance charge carrier mobility, and adjust the oxidation level of PEDOT, leading to improved electrical conductivity and Seebeck coefficient. Structural characterizations reveal that the triple treatment induces conformational changes in PEDOT chains, leading to a more ordered structure and increased crystallinity. The fibers also demonstrate excellent mechanical properties, including high tensile strength and flexibility. The study provides insights into the development of high-performance organic thermoelectric materials through polymer chain modulation. The results demonstrate the potential of the optimized PEDOT:PSS fibers for flexible thermoelectric applications in wearable devices.This study presents an innovative triple post-treatment method for optimizing the thermoelectric performance of wet-spun PEDOT:PSS fibers. The method involves sequential treatments with sulfuric acid (H₂SO₄), sodium borohydride (NaBH₄), and 1-ethyl-3-methylimidazolium dichloroacetate (EMIM:DCA) in methanol. The optimized fibers exhibit a high power factor of (55.4±1.8) μW m⁻¹ K⁻² at 25°C and an output power density of (60.18±2.79) nW cm⁻² at a temperature difference of 10 K. The treatments effectively remove excess insulating PSS, enhance charge carrier mobility, and adjust the oxidation level of PEDOT, leading to improved electrical conductivity and Seebeck coefficient. Structural characterizations reveal that the triple treatment induces conformational changes in PEDOT chains, leading to a more ordered structure and increased crystallinity. The fibers also demonstrate excellent mechanical properties, including high tensile strength and flexibility. The study provides insights into the development of high-performance organic thermoelectric materials through polymer chain modulation. The results demonstrate the potential of the optimized PEDOT:PSS fibers for flexible thermoelectric applications in wearable devices.