In the title compound, [Ho(NO(3))(3)(C(12)H(8)N(2))(2)], the ten-coordinate Ho(III) ion is chelated by four N atoms from two phenanthroline (phen) ligands and six O atoms from three bidentate nitrate groups. The environment around the Ho atom can be described as a distorted bicapped square anti-prism. Two phenanthroline ligands form a dihedral angle of 43.72 (13)°. Short inter-molecular distances between the centroids of the six-membered rings [3.6887 (14)-3.8374 (16) Å] indicate the existence of π-π inter-actions, which link the mol-ecules into stacks extended in the [10] direction. The crystal packing is further stabilized by weak inter-molecular C-H⋯O hydrogen bonds.