A novel photocatalytic method for the synthesis of 1,4-benzoxazepine using 2-alkoxyarylaldehyde as an oxygen source and N-arylglycine as a nitrogen source has been reported. This method is mild, efficient, and fast, and the corresponding reaction can be completed within 2 h at room temperature under a nitrogen atmosphere and light-irradiation conditions. Mechanistic studies have confirmed that this scheme involves the decarboxylation cyclization of N-arylglycine and provides a convenient pathway for the preparation of various 2-alkyl-N-phenyl-substituted 1,4-benzoxazepine.