Ammonia　(NH3)　plays　an　important　role　in　the　development　and　evolution　of　Earth＇s　life　system.　The　extremely　high　bond　energy　(941 kJ　mol−1)　of　N2　hinder　the　conversion　of　N2　to　NH3　under　mild　conditions.　Meanwhile,　clearly　identifying　the　distribution　of　intermediates　for　NH3　synthesis　remains　a　huge　challenge　in　the　experiment.　Herein,　we　anchored　carbon　clusters　(C60　or　C70)　onto　Ru　catalysts　supported　on　rare　earth　oxides,　forming　a　class　of　Ru-carbon　cluster　co-catalysts　that　exhibit　strong　electronic　metal-carbon　cluster　interaction　(EMCI).　Carbon　clusters　function　as　an　electron　buffer　that　induced　electron　uptake　from　metallic　Ru　sites　and　concurrently　provides　electron　feedback　to　Ruδ+　in　a　reversible　manner,　achieving　a　flexible　balance　of　electron　density　at　the　Ru　active　sites.　Moreover,　H-affinitive　carbon　clusters　serve　as　the　site　for　the　adsorption,　activation　and　migration　of　hydrogen.　With　Ru　and　carbon　clusters　synergistically　bridged　by　hydrogen　spillover,　the　Ru-C60　co-catalyst　exhibits　an　exceptionally　high　NH3　synthesis　rate　and　remarkable　stability.　Experimental　provides　direct　evidence　of　the　distribution　and　evolution　of　*N2Hx　(x　=　1∼3)　intermediates,　with　the　hydrogenation　of　*NH2　to　form　*NH3　identified　as　the　rate-determining　step.　This　work　paves　the　way　for　utilizing　carbon　clusters　in　important　chemical　reactions.　©　2024　Wiley-VCH　GmbH.