A facile and effective photo-reduction approach to deposit Pt nanoparticles on MIL-100(Fe) by using a metal–organic framework (MOF) itself as a photoactive catalyst has been developed. The synthesized samples were characterized using X-ray diffraction (XRD), UV-vis diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM) and determining N₂-sorption BET surface area. The as-obtained Pt/MIL-100(Fe) showed photocatalytic activity for H₂ evolution under visible light irradiation and its performance is superior to that of Pt/MIL-100(Fe)–NaBH₄, in which Pt was obtained via reduction by NaBH₄. This work provides an effective and facile approach for the preparation of metal nanoparticles/MOF nanocomposites and demonstrates their potential in solar energy transformations.