The　development　of　highly　active　and　stable　electrocatalysts　toward　oxygen　reduction　reaction　(ORR)　and　hydrogen　evolution　reaction　(HER)　is　a　key　for　commercial　application　of　fuel　cells　and　water　splitting.　Here,　we　report　a　highly　active　and　stable　Pt　nanoparticles　(NPs)　encapsulated　in　ultrathin　two-dimensional　(2D)　carbon　layers　derived　from　the　ultrathin　2D　metal-organic　framework　precursor　(ZIF-67).　Electrochemical　tests　reveal　that　our　approach　not　only　stabilized　Pt　NPs　successfully　but　also　boosted　Pt　activities　toward　ORR　and　HER.　We　found　that　our　Pt　catalysts　encapsulated　in　ultrathin　2D　carbon　layers　exhibited　an　ORR　activity　of　5.9　and　12　times　greater　than　those　of　the　commercial　Pt/C　and　Pt/RGO　without　2D　carbon　layer　protection.　Our　encapsulated　Pt　catalysts　also　show　more　than　nine　times　higher　stability　than　those　of　Pt/C　catalysts.　In　addition　to　ORR,　our　novel　encapsulated　Pt　catalysts　display　an　extraordinary　stability　and　activity　toward　HER,　with　a　lower　overpotential　(14.3　mV　in　acidic　media　and　37.2　mV　in　alkaline　media)　at　a　current　density　of　10　mA　cm-2　than　Pt/C　catalysts　(23.1　mV　in　acidic　media　and　92.1　mV　in　alkaline　media).　The　enhanced　electrochemical　activities　and　stability　of　our　encapsulated　Pt　catalysts　are　attributed　to　the　synergistic　effect　of　Pt-based　NPs　and　ultrathin　2D　carbon　layers　derived　from　ZIF-67　with　enriched　active　sites　Co-Nx.　First-principles　simulations　reveal　that　the　synergistic　catalysis　of　Pt-based　NPs　and　Co-Nx　derived　from　ZIF-67　improves　the　activity　for　ORR　and　HER.　Copyright　©　2020　American　Chemical　Society.