Luminescent　metal　halides　have　attracted　considerable　attention　in　next-generation　solid-state　lighting　because　of　their　superior　optical　properties　and　easy　solution　processibility.　Herein,　we　report　a　new　class　of　highly　efficient　and　dual-band-tunable　white-light　emitters　based　on　Bi3+/Te4+　co-doped　perovskite　derivative　Cs2SnCl6　microcrystals.　Owing　to　the　strong　electron-phonon　coupling　and　efficient　energy　transfer　from　Bi3+　to　Te4+,　the　microcrystals　exhibited　broad　dual-band　white-light　emission　originating　from　the　inter-configurational　P-3(0,1)-＞　S-1(0)　transitions　of　Bi3+　and　Te4+,　with　good　stability　and　a　high　photoluminescence　(PL)　quantum　yield　of　up　to　68.3　%.　Specifically,　a　remarkable　transition　in　Bi3+-PL　lifetime　from　milliseconds　at　10　K　to　microseconds　at　300　K　was　observed,　as　solid　evidence　for　the　isolated　Bi3+　emission.　These　findings　provide　not　only　new　insights　into　the　excited-state　dynamics　of　Bi3+　and　Te4+　in　Cs2SnCl6,　but　also　a　general　approach　to　achieve　single-composition　white-light　emitters　based　on　lead-free　metal　halides　through　ns(2)-metal　ion　co-doping.