Organic thermoelectric fibers have great potential as wearable thermoelectric textiles because of their one-dimensional structure and high flexibility. However, the insufficient thermoelectric performance, high fabrication cost, and mechanical fragility of most organic thermoelectric fibers significantly limit their practical applications. Here, we employ a rapid and cost-effective wet-spinning method to prepare dimethyl sulfoxide-doped poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) fiber bundles, followed by rational post-treatment with concentrated sulfuric acid (98% H2SO4) to enhance their thermoelectric performance. The wearable fiber bundles composed of multiple individual PEDOT:PSS fibers have effectively reduced resistance and overall high tensile strength and stability. Rational treatment with H2SO4 partially removes excessive PSS, thereby increasing the electrical conductivity to 4464 S cm‒1, while the parallel bundle is also a major factor in improving the power factor of up to 80.8 μW m‒1 K‒2, which is super-competitive compared with those of currently published studies. Besides, the thermoelectric device based on these fiber bundles exhibits high flexibility and promising output power of 2.25 nW at a temperature difference of 25 K. Our work provides insights into the fabrication of all-organic flexible high-conductivity textiles with high thermoelectric properties.