To explore alkali-cation selectivity at the chemical reaction level, in this work, we for the first time focused on the different behaviors of potassium and sodium ions in intra- and intermolecular arylation. We prepared a series of aromatic foldamers based on pyridine/oxadiazole alternating sequences as the catalysts for the arylation. Our studies revealed that foldamers can selectively recognize K+ over Na+ and the interactions between foldamers and K+ drive the arylation with a significant yield. In contrast, no trace of the product can be found with Na+. Furthermore, foldamers, with biased handedness, can afford products with optical activity. The balance between two enantiomers of products can be freely controlled by the different conformations of foldamers.