A supramolecular approach was undertaken to create functionally activatable cell‐penetrating peptides. Two tetra‐arginines were assembled into an active cell‐penetrating peptide by heterodimerizing leucine zippers. Three different leucine‐zipper pairs were evaluated: activation was found to depend on the association constant of the coiled‐coil peptides. The weaker‐binding peptides required an additional disulfide linkage to induce cell‐penetrating capability, whereas for the most‐stable coiled‐coil no additional stabilization was needed. The latter zipper pair was used to show that the induced formation of the coiled coils allows control over the uptake of an oligoarginine CPP‐conjugated cargo protein. Springing into action: Activation of a cell‐penetrating peptide can be established through noncovalent coiled‐coil formation. Three different leucine‐zipper peptide pairs were tested for their cell‐penetration upon association by fluorescence analysis. This approach can be extended to whole proteins such GFP.