Three multinuclear gadolinium(III) clusters containing the nicotinate (nic) ligand, [Gd2(nic)6(H2O)4] (1), [Gd4(μ3-OH)4(Hnic)5(H2O)12](ClO4)8·7H2O (2), and [Gd4(μ3-OH)4(nic)6(H2O)6]2(ClO4)4·4H2O (3) were synthesized and characterized. Potential applications of these Gd(III) clusters as high-field magnetic resonance imaging (MRI) contrast agents were evaluated. The longitudinal relaxivities (r1) of 1–3 in water at 7 T were determined to be 10.45 ± 0.16, 9.28 ± 0.06, and 2.04 ± 0.29 mM−1 s−1 on a per Gd ion basis, respectively. In 1% agarose solution, the r1 values increased slightly to 10.37 ± 0.31, 10.74 ± 0.11, and 4.60 ± 0.29 mM−1 s−1 for 1–3, respectively. The ability to tune the number of inner-sphere water molecules, cluster sizes, organic ligands, and Gd coordination modes in such Gd(III) clusters provide interesting opportunities to further enhance the MR relaxivities for potential MRI applications.