Scintillator-based　X-ray　imaging　technology　is　widely　applied　in　medical　diagnostics　and　nondestructive　detection.　Low-dimensional　metal　halide　perovskites　(MHPs)　offer　great　potential　in　scintillation　applications　due　to　their　flexible　crystal　structures.　However,　achieving　strongly　localized　excitonic　emission　in　low-dimensional　MHPs　remains　challenging　to　further　improve　the　photoemission　performance.　Herein,　we　report　an　entropy-engineering　strategy　to　construct　four-element　Cs2MCl6(M　=　Te4+,　Sn4+,　Zr4+,　and　Hf4+)　vacancy-ordered　double-perovskite　scintillators　for　enhanced　X-ray　detection,　demonstrating　an　8-fold　enhancement　in　photoluminescence　quantum　yield,　a　17-fold　enhancement　in　photoluminescence　intensity,　and　a　low　detection　limit　of　50.3　nGy　s–1.　Structural　characterizations　combined　with　theoretical　calculations　reveal　that　increased　configurational　entropy　induces　intense　lattice　distortion　in　[MCl6]2–octahedral　clusters,　increasing　exciton　transport　barriers.　Femtosecond　transient　absorption　and　temperature-dependent　spectroscopic　analyses　indicate　that　this　four-element　Cs2MCl6shows　strong　electron–phonon　and　energy　interactions　between　confined　exciton　states　in　isolated　[MCl6]2–octahedral　structures,　thus　promoting　photoluminescence　emission.　A　flexible　scintillation　screen　containing　high-entropy　Cs2MCl6achieves　a　high　resolution　of　over　20　lp　mm–1for　X-ray　imaging.　This　work　presents　enhanced　emission　of　MHPs　by　entropy　engineering,　providing　potential　implications　for　radiation　detection　and　other　optoelectronic　applications.　©　2025　American　Chemical　Society