A series of novel and synthetically challenging oxazolidinone compounds were synthesized through a regioselective radical addition of azonaphthalenes. In this paper, we developed an iron-catalyzed reduction radical cascade strategy to build poly-substituted oxazolidinones, especially, the synthesis of complex spiro oxazolidinones was of great importance. In addition, the products can also be transformed into unreported and valuable oxadiazin-2-one and β-hydroxyhydrazine compounds.