Transition-metal-free access to carbazoles was achieved through base-mediated intramolecular C–C bond formation. Reactions of N-substituted o-halodiarylamines with potassium tert-butoxide in the presence of ethylene glycol or 1,10-phenanthroline provided carbazoles in moderate to excellent yields. This transformation may proceed through a radical pathway according to a control experiment with a radical scavenger.