Flexible　hybridized　nanogenerators　(FHNGs)　with　multifunctional　piezocomposites　as　core　can　simultaneously　harvest　waste　mechanical　energy　and　thermal　energy　in　the　environment,　which　are　expected　to　replace　chemical　batteries　to　realize　a　long-term　self-power　supply　of　wearable　electronic　devices.　However,　most　reported　piezocomposites　filled　with　low-dimensional　ferroelectric　particles　have　low　piezoelectric　charge　coefficients　together　with　poor　thermal　conductivity,　which　are　not　conducive　to　improving　the　hybridized　generation　power.　In　this　work,　an　effective　design　strategy　with　respect　to　a　reduced　graphene　oxide　(rGO)　nanosheet-decorated　three-dimensional　(3-D)　samarium-doped　Pb(Mg1/3Nb2/3)O-3-PbTiO3　(Sm-PMN-PT)　piezoceramic　skeleton　is　proposed　to　build　high-performance　polydimethylsiloxane　(PDMS)-based　FHNGs.　On　the　one　hand,　rGO　nanosheets　with　high　electrical　conductivity　can　form　an　internal　electric　field　network　to　assist　artificial　polarization　of　the　piezoceramic　skeleton　to　enhance　the　piezoelectric　properties.　On　the　other　hand,　rGO　nanosheets　with　high　thermal　conductivity　can　form　a　heat-transfer　network　to　increase　the　rate　of　temperature　change　over　time　and　improve　the　pyroelectric　properties.　Thanks　to　the　coupling　enhancement　effect　associated　with　rGO　nanosheets,　highly　efficient　concurrent　mechanical　energy　harvesting　(similar　to　0.53　V),　and　thermal　energy　harvesting　(similar　to　0.151　V)　were　realized　in　the　Sm-PMN-PT/PDMS/rGO　piezocomposite,　and　the　total　output　voltage　of　the　FHNG　under　hybrid　excitation　was　as　high　as　0.705　V,　providing　a　promising　paradigm　for　the　development　of　high-performance　FHNG　materials.