<p>Cu(I) halide scintillators have emerged as promising alternatives to conventional X-ray imaging materials, owing to their high luminescence efficiency, structural tunability, and solution processability. Among them, one-dimensional (1D) Cu-I coordination polymers (CPs) not only possess excellent X-ray absorption performance and structural diversity, but also exhibit enhanced stability attributed to their continuous inorganic chain frameworks. However, low radiative efficiency remains a core bottleneck hindering the optoelectronic applications of 1D copper iodide CPs. In this study, ligand halogen engineering is synergistically integrated with the thermally activated delayed fluorescence (TADF) mechanism: halogen electron-withdrawing effects tune the singlet-triplet energy gap (Δ<i>E</i>_ST), while the heavy atom effect boosts orbital coupling, promoting TADF and enabling efficient exciton harvesting. Additionally, the electron-withdrawing property of halogens can further reduce the repulsion between Cu and I, suppressing non-radiative transitions and thereby synergistically enhancing the optical performance and light conversion efficiency of the materials. Herein, two 1D Cu-I CPs were successfully synthesized by introducing different halogen atoms into the ligands: [CuI(3,5-2Cl-py)]_<i>n</i> (<b>SC-Cl</b>, where 3,5-2Cl-py = 3,5-dichloropyridine) and [CuI(3,5-2Br-py)]_<i>n</i> (<b>SC-Br</b>, where 3,5-2Br-py = 3,5-dibromopyridine). Performance characterizations demonstrate that the light yields of <b>SC-Cl</b> and <b>SC-Br</b> reach 14144.4 and 11005.1 photons MeV⁻¹, respectively. The flexible scintillation screens fabricated from these two materials achieve high spatial resolutions of 18.8 and 16.0 lp mm⁻¹ in X-ray imaging. This work not only provides an effective strategy for optimizing the performance of 1D scintillators but also highlights their potential applications in medical diagnosis and security inspection fields.</p>