Strong, tough, and highly conductive polythiophene (PTh) materials are desired for making flexible electronics, but remain as a challenge. Herein, we propose a new strategy to use anionic surfactant as the dopant of PTh to bridge the interaction between the rigid PTh chains and the soft polyethylene glycol (PEG) chains. The dynamic network structure formed by the rigid PTh and the soft PEG could dissipate mechanical energy efficiently, which enables the optimized PTh composite to show both high tensile strength (160 MPa) and high flexibility (elongation-at-break of 110%). The tensile toughness of PTh composite (133 MJ m(-3)) is comparable to that of spider silk, which is the record of the highest toughness in natural materials. We have also established the relationship between the molecular structure of soft polymers and anionic dopants and the electrical and mechanical properties of PTh composites. Meanwhile, the optimized PTh composite also shows a high conductivity (9.5 S cm(-1)) and capacitance (135 F g(-1) at 1 A g(-1) current density). Thus we have fabricated PTh-based flexible conductors and PTh-based flexible supercapacitors to demonstrate its potential applications for flexible electronics.