Extracellular vesicles (EVs) including exosomes have been shown to play crucial roles in cell-to-cell communication because of their ability to carry biofunctional molecules (e.g., microRNAs and enzymes). EVs also have pharmaceutical advantages and are highly anticipated to be a next-generation intracellular delivery tool. Here, we demonstrate an experimental technique that uses arginine-rich cell-penetrating peptide (CPP)-modified EVs to induce active macropinocytosis for effective cellular EV uptake. Modification of arginine-rich CPPs on the EV membrane resulted in the activation of the macropinocytosis pathway, and the number of arginine residues in the peptide sequences affected the cellular EV uptake efficiency. Consequently, the ribosome-inactivating protein saporin-encapsulated EVs modified with hexadeca-arginine (R16) peptide effectively attained anti-cancer activity.