Cell-penetrating peptides (CPPs) play a significant role in the delivery of cargos into human cells. We report the first CPPs based on peptide-bismuth bicycles, which can be readily obtained from commercially available peptide precursors, making them accessible for a wide range of applications. These CPPs enter mammalian cells as demonstrated by live-cell microscopy using fluorescently labelled peptides. We report efficient sequences that demonstrate increased cellular uptake compared …