Developing　efficient　and　simple　catalysts　to　reveal　the　key　scientific　issues　in　the　epoxidation　of　ethylene　has　been　a　long-standing　goal　for　chemists,　whereas　a　heterogenized　molecular-like　catalyst　is　desirable　which　combines　the　best　aspects　of　homogeneous　and　heterogeneous　catalysts.　Single-atom　catalysts　can　effectively　mimic　molecular　catalysts　on　account　of　their　well-defined　atomic　structures　and　coordination　environments.　Herein,　we　report　a　strategy　for　selective　epoxidation　of　ethylene,　which　exploits　a　heterogeneous　catalyst　comprising　iridium　single　atoms　to　interact　with　the　reactant　molecules　that　act　analogously　to　ligands,　resulting　in　molecular-like　catalysis.　This　catalytic　protocol　features　a　near-unity　selectivity　(99%)　to　produce　value-added　ethylene　oxide.　We　investigated　the　origin　of　the　improvement　of　selectivity　for　ethylene　oxide　for　this　iridium　single-atom　catalyst　and　attributed　the　improvement　to　the　π-coordination　between　the　iridium　metal　center　with　a　higher　oxidation　state　and　ethylene　or　molecular　oxygen.　The　molecular　oxygen　adsorbed　on　the　iridium　single-atom　site　not　only　helps　to　strengthen　the　adsorption　of　ethylene　molecule　by　iridium　but　also　alters　its　electronic　structure,　allowing　iridium　to　donate　electrons　into　the　double　bond　π*　orbitals　of　ethylene.　This　catalytic　strategy　facilitates　the　formation　of　five-membered　oxametallacycle　intermediates,　leading　to　the　exceptionally　high　selectivity　for　ethylene　oxide.　Our　model　of　single-atom　catalysts　featuring　remarkable　molecular-like　catalysis　can　be　utilized　as　an　effective　strategy　for　inhibiting　the　overoxidation　of　the　desired　product.　Implementing　the　concepts　of　homogeneous　catalysis　into　heterogeneous　catalysis　would　provide　new　perspectives　for　the　design　of　new　advanced　catalysts.　©　2023　American　Chemical　Society.