In this work, the crystalline structure and supramolecular structure of the poly[sodium cobalt (II) ethylene diaminetetraacetate aqua] complex were studied based on single-crystal X-ray diffraction and Hirschfeld surface analysis. The complex crystallizes in the monoclinic system, in the P21 space group, forming a one-dimensional coordination polymer structure. The Co (II) ion is coordinated in a deformed octahedral geometry through the donor set of the EDTA ligand N2O4. The sodium ion is located in a six-coordinate medium and ensures the formation of the polymer chain by binding neighboring Co-EDTA units. Analysis of the Hirschfeld surface showed that the main interactions determining the stability of the crystal lattice are O···H/H···O hydrogen bonds. In addition, the H···H, O···Na, and O···Co contacts contribute to the strengthening of the supramolecular structure. These results are important for understanding the structural properties of bimetallic coordination polymers based on EDTA and for designing new functional materials.