A rhodium-based multicomponent catalytic system for well-controlled living polymerization of phenylacetylenes has been developed. The catalytic system is composed of readily available and bench-stable [Rh(nbd)Cl]2 , aryl boronic acid derivatives, diphenylacetylene, 50 % aqueous KOH, and PPh3 . This system offers a method for the facile and versatile synthesis of various end-functionalized cis-stereoregular poly(phenylacetylene)s because components from aryl boronic acids and diphenylacetylene were introduced to the initiating end of the polymers. The polymerization reaction shows a typical living nature with a high initiation efficiency, and the molecular weight of the resulting poly(phenylacetylene)s can be readily controlled with very narrow molecular-weight distributions (Mw /Mn =1.02-1.09). The experimental results suggest that the present catalytic system has a higher polymerization activity than the polymerization activities of other rhodium-based catalytic systems previously reported.