Piezoelectric　energy　harvesting　technology　is　drawing　substantial　attention　as　an　eco-friendly　method　to　promote　energy　transformation,　which　is　at　the　forefront　of　current　scientific　research.　However,　the　difficulties　involved　in　obtaining　a　stable　output　voltage　(Vout)　and　a　controllable　output　current　density　(Iout)　represent　bottlenecks　in　the　development　of　piezoelectric　energy　harvesters　(PEHs)　for　practical　applications.　Here,　a　novel　strategy　that　couples　elastic　polarization　configuration　with　activity　rattling　space　in　lead-free　potassium　sodium　niobate-based　piezoceramics　is　proposed　to　break　through　this　barrier.　The　cantilever　beam-type　PEHs　assembled　using　the　rationally　designed　piezoceramic　system　show　a　stable　Vout　(≈22 V)　and　a　controllable　Iout　over　the　range　from　6.09　to　20.16 µA cm−2,　which　is　sufficient　to　drive　multiple　types　of　wireless　sensors　that　have　the　same　rated　voltage　but　different　rated　current　requirements.　These　fantastic　power　generation　performances　are　associated　with　a　stable　piezoelectric　voltage　coefficient　(g33),　an　increasing　piezoelectric　charge　coefficient　(d33),　and　a　weakened　electrostrictive　coefficient　(Q33)　that　stem　from　polarization　configuration　optimization　in　combination　with　introduction　of　the　activity　rattling　space　design.　This　work　provides　a　good　approach　to　modulation　of　the　overall　performance　of　piezoelectric　materials　to　meet　the　demands　of　advanced　PEH　applications.　©　2024　Wiley-VCH　GmbH.