<p>Conjugated polymers are indispensable materials in organic optoelectronics. Living chain-growth polymerization has emerged as a promising strategy for synthesizing conjugated polymers with narrow polydispersity indices. To date, the majority of living chain-growth polymerization protocols have relied on Kumada-type cross-coupling reactions using aryl halides as monomers. Herein, we developed a nickel-catalyzed living chain-growth polymerization method based on carbon–sulfur bond activation, employing aryl sulfides as monomers, which enabled the synthesis of poly(3-hexylthiophene) (P3HT) with a regioregularity exceeding 95%. Kinetic studies confirmed the chain-growth mechanism of the polymerization, while steric hindrance and electronic effects were found to play important roles in regulating the polymerization behavior.</p>