An efficient N-iodosuccinimide-promoted cyclization of readily available alkylidene oxindoles with annular β-dicarbonyl compounds has been demonstrated. With five-membered cyclic β-dicarbonyl compounds as the starting materials, a series of cyclopropyl oxindoles can be obtained in good to excellent yields, whereas it almost quantitatively affords dihydrofuranyl spirooxindoles when six- or seven-membered cyclic β-dicarbonyl compounds are employed. This protocol provides a new alternative to the practical synthesis of structurally diverse spirooxindoles.