The　development　of　high-performance　lead-free　K0.5Na0.5NbO3-based　piezoceramics　for　replacing　commercial　lead-containing　counterparts　is　crucial　for　achieving　environmentally　sustainable　society.　Although　the　proposed　new　phase　boundaries　(NPB)　can　effectively　improve　the　piezoelectricity　of　KNN-based　ceramics,　the　difficulty　of　achieving　saturated　poling　and　the　underlying　multiscale　structures　resolution　of　their　complex　microstructures　are　urgent　issues.　Here,　we　employ　a　medium　entropy　strategy　to　design　NPB　and　utilize　texture　engineering　to　induce　crystal　orientation.　The　developed　K0.5Na0.5NbO3-based　ceramics　enjoys　both　prominent　piezoelectric　performance　and　satisfactory　Curie　temperature,　thus　exhibiting　an　ultrahigh　energy　harvesting　performance　as　well　as　excellent　transducer　performance,　which　is　highly　competitive　in　both　lead-free　and　lead-based　piezoceramics.　Comprehensive　structural　analysis　have　ascertained　that　the　field-induced　efficient　multiscale　polarization　configurations　irreversible　transitions　greatly　encourages　high　saturated　poling.　This　study　demonstrates　a　strategy　for　designing　high-performance　piezoceramics　and　establishes　a　close　correlation　between　the　piezoelectricty　and　the　underlying　multiscale　structures.　There　are　difficulty　of　achieving　saturated　poling　and　understanding　of　multi-scale　structures　in　(K,　Na)NbO3　ceramics.　Here,　the　authors　find　atomic-scale　polymorphic　distortion　and　micrometer-scale　high-density　thin　striped　domains,　which　is　key　for　high　saturated　poling.