Recent advances in cell-penetrating-peptide (CPP)-mediated intracellular protein delivery strategies have highlighted the importance of sustained membrane association to improve delivery efficiency. In this study, we report cell-surface-reactive, polyfluoroalkyl-tagged polyarginine peptides as CPP-additives with varying fluorine content, which enhances cytosolic protein delivery in living cells. We observed that CPP-additives containing 11 13 fluorine atoms significantly enhance intracellular protein delivery relative to a tagless control (> 2-fold) at low micromolar concentrations (2.5 µM) without observable cytotoxicity. Live-cell time-lapse fluorescence imaging revealed that a CPP-additive with 13 fluorine atoms exhibited prolonged membrane association relative to a tagless control (> 5 minutes) and facilitated rapid protein internalization within 10 minutes. Surface-enhanced infrared absorption spectroscopy (SEIRAS) measurements with POPC model membranes indicated that polyfluoroalkylation overall strengthens CPP-additive lipid bilayer interactions. Notably, we found that while fluorous CPP-additives initially interacted with the lipid bilayer predominantly as aggregates, they subsequently inserted into the membrane interior as individual molecules without fluorous tag-tag association. Complementary molecular dynamics simulations of the initial membrane association step provided atomistic insights into these monomeric fluoroalkyl-mediated lipid interactions, revealing partial lipid insertion of an arginine-containing CPP-additive with 13 fluorine atoms while no insertion was observed for a non-fluorinated control at the same time scale. Collectively, our findings introduce polyfluoroalkyl-tagged CPP-additives as potent, non-cytotoxic vectors for intracellular protein delivery and provide mechanistic insights into their monomeric CPP-additive-lipid bilayer interactions.