In the title compound, [Zn(C(8)H(5)O(3))(2)(C(6)H(6)N(2)O)](n), the Zn(II) ion is tetrahedrally coordinated by two formyl-benzoate (FB) and one isonicotinamide (INA) ligands while symmetry-related FB ligands bridge adjacent Zn(II) ions, forming polymeric chains along the b axis. The carboxyl-ate groups in the two FB ions are twisted away from the attached benzene ring by 9.07 (2) and 26.2 (2)°. The two benzene rings of the FB ions are oriented at a dihedral angle of 81.30 (5)°. In the crystal, adjacent polymeric chains inter-act via N-H⋯O and C-H⋯O hydrogen bonds, π-π contacts between the formyl-benzoate rings [centroid-centroid distance = 3.7736 (8) Å] and weak C-H⋯π inter-actions, forming a three-dimensional network.