Semiconductive metal–organic frameworks (MOFs) have attracted extraordinary research interest in recent years; however, electronic applications based on these emerging materials are still in their infancy. Herein, we show that a lanthanide-based semiconductive MOF (SCU-12) can effectively convert X-ray photons to electrical current signals under continuous hard X-ray radiation. The semiconductive MOF-based polycrystalline detection device presents a promising X-ray sensitivity with the value of 23.8 μC Gyair–1 cm–2 under 80 kVp X-ray exposure, competitive with the commercially available amorphous selenium (α-Se) detector. The lowest detectable X-ray dose rate is 0.705 μGy s–1, representing the record value among all X-ray detectors fabricated by polycrystalline materials. This work discloses the first demonstration of hard radiation detection by semiconductive MOFs, providing a horizon that can guide the synthesis of a new generation of radiation detection materials by taking the advantages of structural designability and property tunability in the MOF system.