A number of bioactive molecules possess a 3,3-dimethylazetidine moiety. An iodine-mediated intramolecular cyclization reaction of γ-prenylated amines has been developed to provide a convenient route to 3,3-dimethylazetidines in a highly diastereoselective manner. The presented approach not only offers a new strategy for the synthesis of the bioactively important 3,3-dimethylazetidines but also provides an opportunity to extend the application of γ-prenylated amine synthons in organic synthesis.