A new homometallic cubane-like nickel(II) complex based on N-2-(2-pyridyl)ethyl-2-aminoethanesulfonic acid [Ni4L4(OH)4]·2H2O (I) is synthesized, and its structure is studied by X-ray diffraction (XRD) (CIF file CCDC no. 2211359). In crystals of the complex, the metallocenters are joined into tetrahedra with the Ni…Ni distances (3.144–3.201 Å) supplemented to cubanes by the μ3-bridging oxygen atoms of the hydroxy groups. The coordination environment of each metallocenter is a distorted octahedron. The ligand is deprotonated, exists in the facial conformation, and performs the tridentate function to form two six-membered conjugated chelate cycles.