In this paper we report the preparation and characterization of [Gd(dtpa)]2− intercalated layered double hydroxide (LDH) nanomaterials. [Gd(dtpa)]2− (gadolinium(III) diethylene triamine pentaacetate) was transferred into LDH by anionic exchange. The intercalation of [Gd(dtpa)]2− into LDH was confirmed by X-ray diffraction for the new phase with the interlayer spacing of 3.5–4.0 nm and by FTIR for the characteristic vibration peaks of [Gd(dtpa)]2−. The morphology of the nanoparticles was influenced by the extent of [Gd(dtpa)]2− loading, in which the poly-dispersity quality decreased as the [Gd(dtpa)]2− loading was increased. Compared with the morphology of the original Mg2Al–Cl–LDH nanoparticles (hexagonal plate-like sheets of 50–200 nm), the modified LDH–Gd(dtpa) nanoparticles are bar-like with a width of 30–60 nm and a length of 50–150 nm. LDH–Gd(dtpa) was expected to have an increased water proton magnetic resonance relaxivity due to the intercalation of [Gd(dtpa)]2− into the LDH interlayer that led to slower molecular anisotropic tumbling compared with free [Gd(dtpa)]2− in solution. Indeed, LDH–nanoparticle suspension containing ≈1.6 mM [Gd(dtpa)]2− exhibits a longitudinal proton relaxivity r1 of ≈16 mM−1 s−1 and a transverse proton relaxivity r2 of ≈50 mM−1 s−1 at room temperature and a magnetic field of 190 MHz, which represents an enhancement four times (r1) and 12 times (r2) that of free [Gd(dtpa)]2− in solution under the same reaction conditions. We have thus tailored LDH–nanoparticles into a novel contrast agent with strong relaxivity, promising for great potential applications in magnetic resonance imaging.