Although metal halide-based X-ray scintillators have obtained significant development with adjustable radioluminescent spectral range, the red light-emitting scintillator has been sparsely reported and remains a great challenge until now. To remedy this research blank, we investigated the scintillating property of red light-emissive one-dimensional (1D) organic manganese halide of (MBIZ)(MnCl3H2O)·H2O (MBIZ = 2-methyl-1H-benzoimidazolium) with a high PLQY of 71% under UV light excitation. Remarkably, this manganese halide single crystal exhibits a compelling X-ray scintillating property in the red light spectral range with a light yield of 19 600 photons MeV-1 and detection limit of 0.204 μGy/s, which is significantly better than the standard dosage for X-ray diagnostics. Furthermore, this manganese halide also exhibits excellent radiation resistance ability toward long-term continuous irradiation of high-dose X-ray with stable radiophotoluminescence intensity. Benefiting from the abovementioned combined merits, (MBIZ)(MnCl3H2O)·H2O demonstrates high-performance X-ray imaging with an outstanding spatial resolution of 11.1 lpmm-1. As far as we know, this is an infrequent red-emissive X-ray scintillator in metal halide materials, which highlights a successful structural design concept to explore new manganese halides as more desirable scintillators and expand the application field in medical diagnosis.