The mol-ecule of the title compound, [NaNi(C(18)H(18)N(2)O(4))(C(2)N(3))(H(2)O)], is approximately planar, with a maximum deviation from the mol-ecular plane of 0.770 (5) Å. The coordination environment of the Ni(2+) ion is distorted square-planar and it is N(2)O(2) coordinated by the 6,6'-dimeth-oxy-2,2'-[ethane-1,2-diylbis(nitrilo-methyl-idyne)]diphenolate Schiff base ligand. The Na(+) atom is chelated by the four O atoms of the Schiff base ligand, a water ligand and a dicyanamide anion. The structure displays inter-molecular O-H⋯N hydrogen bonding.