Continuous　progress　of　piezoelectric　coefficient　(d33)　and　dielectric　constant　(εr)　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)O3　is　designed　and　added　into　KNN　ceramic.　This　additive　can　not　only　shift　orthogonal-tetragonal　(O-T)　phase　transition　towards　room　temperature　to　enhance　d33,　but　also　make　the　O-T　phase　transition　becoming　diffusion　in　a　broad　temperature　range.　Furthermore,　the　piezoelectricity　is　further　elevated　by　optimizing　polarization　via　Ce3+　doping.　Finally,　the　enhanced　d33　is　achieved　with　the　excellent　thermal　stability　from　room　temperature　to>　350　°C.　Besides,　the　high　εr　of　~　1150　and　low　dielectric　variation　of　≤　±　15　%　can　be　obtained　in　a　quite　broad　temperature　span　from　room　temperature　to　~　300　°C.　These　overall　performances　of　this　work　show　the　potential　multifunctional　applications　in　high-temperature　piezoelectric　and　dielectric　devices.　©　2022　Elsevier　B.V.