Surface-enhanced　Raman　Scattering　(SERS)　is　a　sensitive　and　nondestructive　technique　that　provides　fingerprint　structural　information　of　molecules.　Designing　and　constructing　sensitive　and　stable　SERS　substrates　is　of　great　significance　for　the　application　of　the　technique.　In　this　study,　single-layer　carbon-based　dots　(CDs)　are　used　as　capping　agents　to　synthesize　gold　nanoparticles　(AuNPs/CDs)　and　manganese　dioxide　nanosheets　(MnO2/CDs),　which　are　then　hybridized　through　a　simple　cocentrifugation　method.　After　the　hybridization,　the　monodispersive　AuNPs/CDs　aggregate　obviously　into　some　clusters　exhibiting　strong　SERS　activity　due　to　the　electromagnetic　＇hot　spots＇effect,　and　the　MnO2/CDs　also　show　outstanding　SERS　activity　due　to　the　charge-transfer　resonance　effect.　The　obtained　nanohybrids　(MnO2/CDs/AuNPs)　with　robust　chemical　stability　combine　well　with　the　electromagnetic　enhancement　of　AuNPs/CDs　and　chemical　enhancement　of　MnO2/CDs,　leading　to　an　ultrahigh　enhancement　factor　of　3.9　×　108.　Based　on　the　novel　SERS　substrate,　a　sensitive　and　rapid　sensing　system　for　the　detection　of　malachite　green　is　developed,　with　a　low　detection　limit　of　1　×　10-9　M.　This　work　provides　a　valuable　model　for　designing　and　fabricating　high-performance　SERS　substrates.　©　2021　American　Chemical　Society.