Site-selective cleavage of amide bonds in peptide and protein constitutes a valuable modification that has found a wide spectrum of applications in proteomics, chemical biology, and drug development. Here we describe a novel tyrosine-selective peptide cleavage method enabled by Dess–Martin periodinane. This reaction leads to the breakdown of the N-terminal amide bond of tyrosine, generating a C-terminal peptide fragment bearing an unusual hyperoxidized tyrosine motif, 4,5,6,7-tetraoxo-1H-indole-2-carboxamide, along with an intact N-terminal peptide fragment. Application of this methodology to the sequencing of a few cyclic peptides containing tyrosine residues has been readily achieved.