In the title complex, [Na(C7H7O4S)] n , the Na(I) ion is coord-inated in a slightly distorted penta-gonal-bipyramidal environment by seven O atoms [Na-O = 2.3198 (16)-2.5585 (17) Å]. The 4-methoxybenzenesulfonate anions act as bis-chelating and bridging ligands, forming a two-dimensional polymer parallel to (001), which is further linked into a three-dimensional network by weak C-H⋯O hydrogen bonds.