Dy3+-doped　K0.5Na0.5NbO3-Ba(Sc0.5Nb0.5)O3　transparent　ferroelectric　ceramics,　a　novel　smart　white-lighting　(WL)　photochromic　(PC)　material,　were　prepared　by　conventional　pressureless　sintering.　The　ceramics　exhibit　high　optical　transmittance　(~67%　at　1800 nm),　good　photoluminescence　(PL)　performance,　high-quality　WL,　and　moderate　electrical　properties.　Meanwhile,　high-contrast　modulations　of　optical　transmittance　and　PL　intensity　(with　the　maximal　modulating　values　of　20.5%　and　57.4%,　respectively)　have　been　realized　via　PC　behavior　by　alternating　the　illumination　of　UV　light　and　thermal　stimulus.　In　particular,　the　reversible　modulations　of　WL　intensity,　color　coordinates,　correlated　color　temperature,　and　color　purity　have　been　achieved　through　the　PC　regulation　to　the　intensity　ratio　of　yellow/blue　emission.　Definitively,　based　on　the　effect　of　intrinsic　defects　and　extrinsic　defects　(Ba4+/Sc3-x)　on　the　PL　properties,　the　PC　mechanism　in　KNN-based　material　has　been　further　complemented.　The　transparent　ceramics　should　be　a　promising　material　in　white　LEDs　and　optoelectronic　multifunctional　devices.　©　2020　American　Ceramic　Society　(ACERS)