Due　to　the　higher　value　of　deeply-reduced　products,　electrocatalytic　CO2　reduction　reaction　(CO2RR)　to　multi-electron-transfer　products　has　received　more　attention.　One　attractive　strategy　is　to　decouple　individual　steps　within　the　complicated　pathway　via　multi-component　catalysts　design　in　the　concept　of　tandem　catalysts.　Here,　a　composite　of　Cu@BIF-144(Zn)　(BIF　=　boron　imidazolate　framework)　is　synthesized　by　using　an　anion　framework　BIF-144(Zn)　as　host　to　impregnate　Cu2+　ions　that　are　further　reduced　to　Cu　nanoparticles　(NPs)　via　in　situ　electrochemical　transformation.　Due　to　the　microenvironment　modulation　by　functional　BH(im)3−　on　the　pore　surfaces,　the　Cu@BIF-144(Zn)　catalyst　exhibits　a　perfect　synergetic　effect　between　the　BIF-144(Zn)　host　and　the　Cu　NP　guest　during　CO2RR.　Electrochemistry　results　show　that　Cu@BIF-144(Zn)　catalysts　can　effectively　enhance　the　selectivity　and　activity　for　the　CO2　reduction　to　multi-electron-transfer　products,　with　the　maximum　FECH4　value　of　41.8%　at　−1.6 V　and　FEC2H4　value　of　12.9%　at　−1.5 V　versus　RHE.　The　Cu@BIF-144(Zn)　tandem　catalyst　with　CO-rich　microenvironment　generated　by　the　Zn　catalytic　center　in　the　BIF-144(Zn)　skeleton　enhanced　deep　reduction　on　the　incorporated　Cu　NPs　for　the　CO2RR　to　multi-electron-transfer　products.　©　2023　Wiley-VCH　GmbH.