We report, for the first time, manganese-mediated direct functionalization of the Hantzsch esters with readily accessible alkyl iodides through an aromatization-dearomatization strategy. Applying this protocol, a library of valuable 4-alkyl-1,4-dihydropyridines were facilely afforded in good yields. This simple and practical reaction proceeds under visible-light irradiation at room temperature and displays high functional-group compatibility. Additionally, the method is applicable for gram-scale synthesis and late-stage functionalization of complex molecules.