In the title salt, [K(C(10)H(9)O(4))](n), the K(+) ions are coordinated by six O atoms from three different anions, and there is a cation-π inter-action at ca 3.14 Å. The 2-[2-(carboxymethyl)phenyl]acetate anions are stabilized by intramolecular O-H⋯O hydrogen bonds, and the K(+) cations are linked into one-dimensional coordination polymers running along the b axis; these are further inter-connected by weak C-H⋯O hydrogen bonds.