Large　piezoelectric　voltage　coefficient　(g33)　and　figure　of　merit　(FOM33)　are　the　key　parameters　of　perovskite　ceramics　for　piezoelectric　sensors　and　energy　harvesters.　Here,　the　Bi(Zn2/3Nb1/3)O3　(BZN)　member　with　a　low　tolerance　factor　is　introduced　into　the　BiScO3-PbTiO3　(BS-PT)　perovskite　high-temperature　piezoelectric　matrix　to　decouple　the　piezoelectric　coefficient　(d33)　and　dielectric　constant　(εr)　by　modulating　the　morphotropic　phase　boundary　and　grain　size.　For　the　optimal　0.38BS-0.01BZN-0.61PT　ceramic　that　benefits　from　the　decoupling　of　d33　and　εr,　its　Curie　temperature,　g33　and　FOM33　are　as　high　as　436　°C,　38.6　mV·m·N−1　and　16.5×10−12　m2·N−1,　respectively.　Furthermore,　the　0.38BS-0.01BZN-0.61PT　ceramic　also　shows　the　technical　advantages　of　large　g33　and　FOM33　even　at　harsh　elevated　temperatures　(≥　200　°C).　Due　to　its　outstanding　comprehensive　performances　above,　the　0.38BS-0.01BZN-0.61PT　ceramic　surpasses　many　other　BS-PT-based　piezoceramics.　These　results　demonstrate　that　the　0.38BS-0.01BZN-0.61PT　material　is　a　promising　competitor　for　high-temperature　electromechanical　coupling　applications.　©　2024　Elsevier　Ltd