We report a cobalt/sodium dispersion (SD) catalytic system for the imine-directed, branched-selective hydroarylation of styrenes. Sodium dispersion serves as a convenient reductant to generate catalytically active low-valent cobalt species in situ, avoiding the use of Grignard reagents or preformed air-sensitive complexes. A range of aromatic ketimines and styrenes undergo branched-selective hydroarylation in good yields with high regioselectivity characteristic of cobalt catalysis and distinct from Murai-type reactivity under mild conditions.