​To address the challenge of removing unwanted anions from aqueous media under extraction‐free conditions we have prepared a thermoresponsive amphiphilic polymer with pendent calix[4]pyrrole (C4P) receptors. Because of its amphipathicity, this polymer self‐assembles into micelles in water. These micelles contain the C4P receptors buried in a hydrophobic core. This allows uptake of various cesium anions into the micelles. Due to the thermal responsiveness of the hydrophilic block chain, the anion‐bearing micelles precipitate in water upon heating. Simple filtration allows their removal from the aqueous environment, thus allowing for effective water purification. Treating the anion‐trapped micelles with acidic aqueous solution leads to the competition‐induced release of the bound anion and thus recycling the polymeric material.