The　development　of　advanced　nonprecious-metal　catalysts　for　efficient　ammonia　(NH3)　synthesis　under　mild　conditions　represents　significant　importance.　However,　the　incompatibility　between　facile　N2activation　and　NH3desorption　in　monometallic　catalysts　limits　their　catalytic　activity　for　NH3synthesis.　Herein,　we　systematically　fabricated　CoRexalloy　(x　=　0.25,　0.5,　0.75,　1,　1.5,　and　2)　catalysts　by　modulating　the　Co/Re　ratio　to　achieve　efficient　NH3synthesis.　Our　studies　reveal　that　the　Co/Re　ratio　in　CoRexcatalysts　critically　governs　the　formation　of　Co–Re　paired　sites,　with　the　quantity　of　these　pairs　demonstrating　a　strong　positive　correlation　with　the　NH3synthesis　rates.　Excess　Co　(CoRe0.5)　or　Re　(CoRe2)　leads　to　either　insufficient　N2activation　or　excessively　strong　NH3adsorption,　both　detrimental　to　catalytic　efficiency.　In　contrast,　the　CoRe1alloy　featuring　abundant　Co–Re　pairs　simultaneously　realizes　the　facile　N2activation　and　NH3desorption　through　a　synergistic　effect　of　Co–Re　orbital　hybridization.　Consequently,　the　optimized　CoRe1delivers　a　remarkable　NH3synthesis　rate　of　12.0　mmol　gcat–1h–1at　400　°C　and　1　MPa,　surpassing　those　of　most　reported　NPM　catalysts　to　date.　©　2025　American　Chemical　Society