The title Co-II complex, [Co(C9H10NO2)(2)(C6H6N2O)(H2O)(2)], contains two 4-dimethylaminobenzoate (DMAB) anions, one isonicotinamide (INA) ligand and two coordinated water molecules. One of the DMAB anions acts as a bidentate ligand, while the other is monodentate. The four O atoms in the equatorial plane around the Co atom form a highly distorted square-planar arrangement, while the distorted octahedral coordination geometry is completed by the N atom of the INA ligand and the O atom of the second water molecule in the axial positions. An intramolecular O-H center dot center dot center dot O hydrogen bond between the monodentate-coordinated carboxyl group and a coordinated water molecule results in a six-membered ring with an envelope conformation. The dihedral angles between the carboxyl groups and the adjacent benzene rings are 4.29 (10)degrees for the monodentate ligand and 2.31 (13)degrees for the bidentate ligand, while the two benzene rings are oriented at a dihedral angle of 65.02 (5)degrees. The dihedral angles between the pyridine and benzene rings are 11.21 (5)degrees for the monodentate ligand and 74.60 (5)degrees for the bidentate ligand. In the crystal structure, intermolecular O-H center dot center dot center dot O, O-H center dot center dot center dot N and N-H center dot center dot center dot O hydrogen bonds link the molecules into a supramolecular structure.