Crystal　defects　and　morphological　modifications　are　popular　strategies　to　enhance　the　catalytic　activity　of　heterogeneous　semiconductor　photocatalysts.　Despite　defect　engineering　and　morphology　control　show　their　successful　applications　in　ZnO,　the　effects　of　curved　surface　modifications　on　the　photocatalytic　performance　of　ZnO　and　their　interplay　with　the　defect　formation　remain　unclear.　To　resolve　this　puzzle,　we　systemically　investigate　the　joint　effects　of　curvature　and　defect　formation　on　the　electronic　structure,　optoelectronic　properties,　and　photocatalytic　performance　of　ZnO　slabs　using　first-principles　calculations.　We　find　that　curvature　deformation　effectively　narrows　the　electronic　bandgap　by　up　to　1.6　eV　and　shifts　the　p-/d-band　centers,　thereby　enhancing　light　absorption　in　the　visible　and　near-ultraviolet　regions.　Besides,　curvature　deformation　stimulates　self-polarization,　facilitating　the　separation　of　photogenerated　electrons　and　holes.　Also,　curvature　deformation　promotes　the　formation　of　defects　by　reducing　defect　formation　energy　(by　up　to　1.0　eV),　thus　creating　abundant　reaction　sites　for　photocatalysis.　Intriguingly,　the　synergistic　interaction　between　curvature　and　defect　deformation　further　strengthens　the　self-polarization,　narrows　the　electronic　bandgaps,　adjusts　the　p-/d-band　centers　to　improve　the　optoelectronic　properties,　and　influences　the　dissociation　and　free　energy　barriers　of　intermediates.　Consequently,　our　findings　reveal　that　this　synergy　substantially　enhances　the　photocatalytic　performance　of　ZnO　slabs,　providing　deeper　insights　into　the　role　of　defect　engineering　and　morphology　control　on　photocatalysis.　(c)　2025　Published　by　Elsevier　B.V.　on　behalf　of　Chinese　Chemical　Society　and　Institute　of　Materia　Medica,　Chinese　Academy　of　Medical　Sciences.