<p>Fiber-reinforced conducting polymer composites have gained significant attention as functional materials for electronic devices. However, sustainable approaches have received less attention. This study presents a sustainable, cost-effective, and facile method for producing electronically conductive fibers by transforming rayon fibers (RFs), a type of regenerated cellulose fiber, into conductive RFs with washing durability. The cuprammonium rayon has been produced and conductivity was imparted through dip coating once with poly (3,4-ethylenedioxythiophene): poly (styrene sulfonate) (PEDOT: PSS) polymer and post-treatment with ethylene glycol (EG). The electrical resistance of the bare RF decreased by three orders of magnitude, from 23.50 ± 0.71 MΩ cm⁻¹ to 30.45 ± 0.54 kΩ cm⁻¹, after a single dip-coating with PEDOT:PSS. Following EG post-treatment, the resistance was further reduced by approximately 20-fold to 1.38 ± 0.10 kΩ cm⁻¹, due to EG-induced conformational changes in the PEDOT:PSS structure. Successful coating of PEDOT:PSS on RF was observed with Fourier transform infrared spectroscopy. Surface modifications were studied using scanning electron microscopy and bright field microscopy. Moreover, mechanical properties were investigated, and a higher breaking load of 0.2 N and tensile strength of 176.28 N/mm² were demonstrated. The developed fiber exhibited reasonably good washing stability with aqueous detergent medium as well as tetrachloroethylene solvent. Further, the modified RFs present in this study are a promising candidate as fiber electrodes, particularly where sustainable solutions are imperative.</p> Graphical Abstract <p></p>