Long-lasting　radioluminescence　scintillators　have　recently　attracted　substantial　attention　from　both　research　and　industrial　communities,　primarily　due　to　their　distinctive　capabilities　of　converting　and　storing　X-ray　energy.　However,　determination　of　energy-conversion　kinetics　in　these　nanocrystals　remains　unexplored.　Here　we　present　a　strategy　to　probe　and　unveil　energy-funneling　kinetics　in　NaLuF4:Mn2+/Gd3+　nanocrystal　sublattices　through　Gd3+-driven　microenvironment　engineering　and　Mn2+-mediated　radioluminescence　profiling.　Our　photophysical　studies　reveal　effective　control　of　energy-funneling　kinetics　and　demonstrate　the　tunability　of　electron　trap　depth　ranging　from　0.66　to　0.96　eV,　with　the　corresponding　trap　density　varying　between　2.38×105　and　1.34×107　cm−3.　This　enables　controlled　release　of　captured　electrons　over　durations　spanning　from　seconds　to　30　days.　It　allows　tailorable　emission　wavelength　within　the　range　of　520–580　nm　and　fine-tuning　of　thermally-stimulated　temperature　between　313–403　K.　We　further　utilize　these　scintillators　to　fabricate　high-density,　large-area　scintillation　screens　that　exhibit　a　6-fold　improvement　in　X-ray　sensitivity,　22　lp/mm　high-resolution　X-ray　imaging,　and　a　30-day-long　optical　memory.　This　enables　high-contrast　imaging　of　injured　mice　through　fast　thermally-stimulated　radioluminescence　readout.　These　findings　offer　new　insights　into　the　correlation　of　radioluminescence　dynamics　with　energy-funneling　kinetics,　thereby　contributing　to　the　advancement　of　high-energy　nanophotonic　applications.　©　2024　Wiley-VCH　GmbH.