Here we describe the utility of peptide macrocyclization through perfluoroaryl-cysteine SNAr chemistry to improve the ability of peptides to cross the blood-brain barrier. Multiple macrocyclic analogues of the peptide transportan-10 were investigated that displayed increased uptake in two different cell lines and improved proteolytic stability. One of these analogues (M13) exhibited substantially increased delivery across a cellular spheroid model of the blood-brain barrier. Through ex vivo imaging of mouse brains, we demonstrated that this perfluoroarene-baed macrocycle of TP10 exhibits increased penetration of the brain parenchyma following intravenous administration in mice. Finally, we evaluated macrocyclic analogues of the BH3 domain of the BIM protein to assess if our approach would be applicable to a peptide of therapeutic interest. We identified a BIM BH3 analogue that showed increased penetration of the brain tissue in mice.