Montmorillonite (Mnt), a clay mineral with a nanolayered structure, was combined with an Fe-based metal–organic framework (MOF; MIL-53(Fe)) using an in situ growth technique that yielded a novel eco-friendly clay-based adsorbent (MIL-53(Fe)@Mnt). The adsorbent was characterized by scanning electron microscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis and N2 gas adsorption. The MIL-53(Fe) particles grew on the surface of the nanolayered Mnt and the MIL-53(Fe) particle size became smaller. The adsorption performance of MIL-53(Fe)@Mnt was investigated by removing methylene blue (MB), and optimization experiments were carried out to study the effects of contact time, pH, initial dye concentration and adsorbent mass on the adsorption processes. The MIL-53(Fe)@Mnt exhibited excellent adsorption capacity for MB, namely 313.7 mg g−1, which was 3.02 times and 3.54 times greater than that of pure Mnt and MIL-53(Fe), respectively. Adsorption was fitted with the Langmuir isotherm model and followed a pseudo-second order kinetic model. The MIL-53(Fe)@Mnt obtained is a low-cost and eco-friendly adsorbing material and might be a candidate for removing dyes during water treatment.