Iridium　(Ir)　single-atom　catalysts　(SACs)　exhibit　extraordinary　advantages　in　the　oxygen　evolution　reaction　(OER)　owing　to　their　unique　electronic　structure　and　maximized　atom　utilization.　However,　further　developments　have　met　with　bottlenecks　due　to　the　limited　catalytic　activity　derived　from　the　widely　adopted　adsorbate　evolution　mechanism　(AEM)　pathway　in　Ir　SACs　for　OER.　Herein,　we　report　an　efficient　strategy　to　improve　the　intrinsic　activity　of　Ir　SACs　by　anchoring　atomic　Ir　on　an　oxygen　vacancy-modified　CoNiO2　support　(Ir-SA-V-O-CoNiO2),　in　which　a　more　advanced　lattice　oxygen　oxidation　(LOM)　pathway　is　constructed　by　activating　lattice　oxygen　to　participate　in　OER.　Specifically,　the　synthesized　CoNiO2　support　could　provide　the　weak　metal-oxygen　bond　and　facilitate　the　movement　and　conversion　of　lattice　oxygen.　The　oxygen　vacancies　provided　abundant　active　sites　for　the　adsorption　of　OH*　and　induced　a　substantial　O　2p　characteristic　near　the　Fermi　level　for　activating　the　lattice　oxygen　in　CoNiO2.　Moreover,　the　introduction　of　Ir　atoms　in　the　oxygen　vacancies　modulated　CoNiO2　results　in　the　significant　overlap　between　the　Ir　5d　and　O　2p　bands　and　constructed　a　stronger　Ir-O　covalent　bond,　which　extremely　facilitated　the　transformation　from　O-O　to　OO*　for　boosting　the　final　O-2　evolution.　Through　the　above-mentioned　results,　a　more　efficient　LOM　pathway　in　the　single-atom　Ir　catalyst　was　constructed,　and　the　as-synthesized　Ir-SA-V-O-CoNiO2　displayed　outstanding　OER　performance　with　10　mA　cm(-2)　at　a　low　overpotential　of　183　mV　and　a　high　mass　activity　of　5　A　mg(-1)　at　the　overpotential　of　300　mV,　significantly　outperforming　the　reported　catalysts.　This　work　proposes　an　advanced　channel　to　design　efficient　electrocatalysts　for　promising　OER　applications.