We report on a series of experiments on hydrogels formed by supramolecular hairy-rod conjugated polymers and their lyotropic liquid crystalline behavior. The system is an ionic complex between negatively charged poly[2-(3-thienyl)ethyloxy-4-butylsulfonate)] backbones and cationic cetrimonium side chains. These hairy-rod supramolecules form stable isotropic solutions under dilute conditions with enhanced photoluminescence relative to the neat polymer itself. The system displays an isotropic-liquid crystalline transition on increasing concentration, resulting in the formation of a hexagonally ordered lyotropic mesophase in which the polymer chains are packed into hexagonally ordered rod-like assemblies. The mesophase is thermosensitive and can be isotropized by moderate heating. Although theoretically predicted, the observation of such lyotropic mesophases in conjugated polymers has not been reported to date. The results here are rationalized in terms of the uncharacteristically long side chains and inherent polydispersity of the system which appear necessary for stabilization of this mesophase. These results may provide new routes for the fabrication of well ordered conjugated polymer films from such solution ordered precursors for high performance electro-optic devices.