Currently,　effective　piezoelectric　energy　harvesters　are　based　on　Pb(Zr,　Ti)O-3　(PZT)　ceramics.　However,　the　growing　environmental　concerns　have　been　pushing　the　development　of　viable　green　alternatives　for　lead-based　piezoelectric　ceramics.　In　this　study,　a　high　quality　Mn-modified　(K0.5Na0.5)　NbO3　(Mn-KNN)　lead-free　piezoelectric　ceramic　has　been　prepared,　which　is　promising　for　use　in　lead-free　piezoelectric　energy　harvesters.　Herein,　we　showed　that　the　1.0　mol%　Mn-KNN　ceramics　not　only　possessed　high　Curie　temperature,　but　also　exhibited　excellent　energy　harvesting　performance　due　to　the　highly　dense　fine-grained　structure　and　various　domain　configurations.　In　the　mode　of　a　cantilever-type　energy　harvester,　a　high　output　power　of　85　mu　W　and　peak-to-peak　voltage　of　16　V　were　obtained　at　the　acceleration　of　40　m　s(-2).　Furthermore,　the　1.0　mol%　Mn-KNN　energy　harvester　exhibits　excellent　fatigue　resistance　up　to　10(6)　cycles.　These　findings　indicate　potential　applications　of　the　Mn-KNN　piezoelectric　energy　harvester　for　self-powered　sources　of　wireless　sensor　network　systems.