Nanocrystal scintillators have attracted considerable attention due to their attractive facile solution-processed thin-film fabrication and tunable X-ray luminescence, and thus hold promise for manufacturing next-generation scintillation screens for high-resolution X-ray imaging. Current inorganic scintillators usually have drawbacks of time-consuming preparation, toxic components, and rigorous synthesis conditions at a relatively high temperature. Here, we report a one-pot green synthesis strategy for readily scaling-up preparation of eco-friendly, lanthanide-doped NaBiF4 nanoscintillators. These nanoscintillators feature efficient X-ray absorption due to the high-Z bismuth element and tunable radioluminescence in the visible region through rational lanthanide doping. We demonstrate a laminating-annealing technology to fabricate large-area scintillation screen (Ø = 5 cm) using these NaBiF4 nanoscintillators for high-resolution X-ray imaging with a spatial resolution of 9 line pairs per millimeter (lp mm−1). Our study offers new ways to transport low-cost synthesis of high-quality nanoscintillators for high-performance digital radiography.