A unique Co(III)-catalyzed and DMSO-involved C-H activation/cyclization of simple, cheap, and easily available anilines with alkynes for direct and highly efficient synthesis of privileged quinolines with exclusive regioselectivity and broad substrate/functional group tolerance and in good to excellent yields, where DMSO was employed as both the solvent and the C1 building block of quinoline products, is reported. Mechanistic experiments revealed that the versatile reaction might employ the 2-vinylbenzenamine species as the active intermediate.