Gadolinium(III) nanoconjugate constrast agents (CAs) have distinct advantages relative to their small molecule counterparts in magnetic resonance imaging (MRI). In addition to increased Gd(III) payload, a significant improvement in contrast enhancement efficiency, or relaxivity (r1) is often observed. In this work, we describe the synthesis and characterization of a nanoconjugate CA created by covalent attachment of Gd(III) to thiolated DNA (Gd(III)-DNA), followed by surface conjugation onto gold nanostars (DNA-Gd@stars). These conjugates exhibit remarkable r1 with values up to 98 mM(-1) s(-1). Additionally, DNA-Gd@stars show efficient Gd(III) delivery and biocompatibility in vitro and generate significant contrast enhancement when imaged at 7T. Using nuclear magnetic relaxation dispersion (NMRD) analysis, we attribute the high performance of the DNA-Gd@stars to an increased contribution of second-sphere relaxivity compared to that of spherical CA equivalents (DNA-Gd@spheres). Importantly, the surface of the gold nanostar contains Gd(III)-DNA in regions positive, negative, and neutral curvature. We hypothesize that the proton relaxation enhancement observed results from the presence of a unique hydrophilic environment produced by Gd(III)-DNA in these regions, which allows second-sphere water molecules to remain adjacent to Gd(III) ions for up to ten times longer than diffusion. These results establish that particle shape, and second sphere relaxivity are important considerations in the in the design of Gd(III) nanoconjugate CAs.