Continuous　progress　of　piezoelectric　coefficient　(d(33))　and　dielectric　constant　(epsilon(r))　are　obtained　in　(K,　Na)　NbO3　(KNN)-based　lead-free　piezoceramics　by　phase　boundary　formation,　while　usually　accompanying　by　the　poor　temperature　thermal　stability,　which　are　not　conductive　to　actual　applications.　In　this　work,　the　perovskite-type　compound　Bi(Ni2/3Nb1/3)O-3　is　designed　and　added　into　KNN　ceramic.　This　additive　can　not　only　shift　orthogonal-tetragonal　(O-T)　phase　transition　towards　room　temperature　to　enhance　d(33),　but　also　make　the　O-T　phase　transition　becoming　diffusion　in　a　broad　temperature　range.　Furthermore,　the　piezo-electricity　is　further　elevated　by　optimizing　polarization　via　Ce3+　doping.　Finally,　the　enhanced　d(33)　is　achieved　with　the　excellent　thermal　stability　from　room　temperature　to　＞　350　degrees　C.　Besides,　the　high　epsilon(r)　of　1150　and　low　dielectric　variation　of　＜=　+/-　15　%　can　be　obtained　in　a　quite　broad　temperature　span　from　room　temperature　to　similar　to　300　degrees　C.　These　overall　performances　of　this　work　show　the　potential　multifunctional　applications　in　high-temperature　piezoelectric　and　dielectric　devices.　(C)　2022　Elsevier　B.V.　All　rights　reserved.