Eco-friendly　(K,　Na)NbO3　(KNN)-based　electrostrictive　materials　have　attracted　increasing　attention　as　potential　candidates　for　high-precision　displacement　actuators.　Although　a　series　of　breakthroughs　have　increased　the　electrostrictive　coefficient　of　KNN-based　materials　with　relaxor　behaviour　(Q33　>　0.0450　m4/C2),　the　electrostrictive　strain　is　still　low　(<0.1%),　making　the　improvement　of　the　electrostrictive　strain　a　crucial　next　step.　Here,　a　KNN-based　relaxor　ceramic　of　0.96K0.48Na0.52Nb1-xSbxO3-0.04Bi0.5Na0.5ZrO3-0.3%Fe2O3　(KNNSx-BNZ)　was　designed　to　simultaneously　achieve　high　electrostrictive　strain　and　Q33.　The　phase　structure　transformed　from　the　T　phase　to　the　C　phase　with　increasing　Sb　concentration,　which　also　introduced　fine　grains　and　domains.　A　high　electrostrictive　strain　(∼0.102%)　and　Q33　(∼0.0461　m4/C2)　were　obtained　at　x　=　0.09　through　a　small　adjustment　of　the　structure　of　the　relaxor,　while　an　electrostrictive　strain　with　low　hysteresis　(<10.5%)　and　an　outstanding　temperature　stability　(≥95%)　were　achieved　in　the　broadened　temperature　range　of　20–180　°C,　representing　properties　superior　to　those　of　previous　KNN-based　and　typical　PZT-based　materials.　Our　results　will　help　researchers　understand　how　to　balance　the　strain　and　electrostrictive　coefficient　in　lead-free　materials,　and　thereby　contribute　toward　accelerating　the　application　of　KNN-based　electrostrictive　materials　in　actuators.　©　2022　Elsevier　Ltd　and　Techna　Group　S.r.l.