Molecular　transition　metal　complexes　are　widely　explored　in　artificial　photosynthetic　redox　catalysis　due　to　their　extraordinary　properties.　However,　these　catalysts　generally　suffer　from　the　intrinsic　thresholds　of　photon　harvesting　efficiency　and　spectrum　response　range,　greatly　limiting　their　further　applications.　Polypyridyl　ruthenium　(Ru)　has　been　perceived　as　a　paradigmatic　photosensitizer　in　CO2　reduction　systems　but　seldomly　maneuvered.　Herein,　we　develop　a　novel　and　practicable　pseudo-supramolecular　assembly　at　a　molecular　scale　by　conjugation　with　ultra-small　nitrogen-doped　carbon　quantum　dots　(NCQDs)　as　ultraviolet-visible　(UV–vis)　light　chromophore　for　enhanced　photochemical　conversion　of　CO2　to　CO.　The　reversible　self-assembly　of　NCQDs　with　Ru　is　driven　by　dynamic　non-covalent　π-conjugated　and　electrostatic　interactions.　Femtosecond　transient　absorption　and　time-resolved　fluorescence　decay　spectra　combined　with　control　experiment　results　collaboratively　demonstrate　that　vectorial　photo-induced　exciton　cascade　occurs　by　means　of　their　unique　photophysical　properties　in　the　as-assembled　NCQDs/Ru　dyad,　enabling　the　superior　photosensitized　CO2　reduction　performance　in　both　homogeneous　and　heterogeneous　systems.　This　work　is　expected　to　not　only　shed　new　light　on　the　development　of　promising　artificial　light-harvesting　systems　but　also　promote　the　implementation　of　metal　complex-based　systems　for　photoredox-catalyzed　reactions.　©　2021　Elsevier　B.V.