Photocatalytic　ozonation　emerges　as　an　appealing　approach　for　wastewater　purification.　However,　the　kinetic　constraints　associated　with　the　charge　separation　and　the　ozone　activation　hinder　the　advancement　of　photocatalytic　ozonation　systems.　Herein,　we　prepared　CeO2　photocatalysts　with　predominantly　exposed　{1　1　0},　{1　0　0},　or　{1　1　1}　facets,　highlighting　the　synergy　role　of　crystal　facet　and　oxygen　vacancies　in　manipulating　electron　transfer　and　ozone　activation.　The　CeO2-{1　1　0}　catalyst　exhibits　the　best　efficiency　for　phenol　mineralization　(69%)　in　photocatalytic　ozonation.　Ex-situ,　Quasi-situ,　and　In-situ　characterization　of　the　CeO2　catalysts　reveal　that　facet　engineering　in　the　CeO2　catalysts　optimizes　the　electronic　properties　of　the　catalysts,　thereby　enhancing　the　separation　of　photogenerated　charge　carriers　and　transfer　of　electrons　and　holes,　which　provides　more　electrons　for　O3　activation　and　promotes　the　formation　of　reactive　oxygen　species　(ROS).　Moreover,　facet　modulating　leads　to　a　change　in　the　density　of　surface　oxygen　vacancies.　The　increased　oxygen　vacancy　density　on　the　CeO2-{1　1　0}　surface　accelerates　the　activation　of　O3　and　the　formation　of　adsorbed　oxygen　(*O),　synergistically　boosting　the　production　rate　of　ROS.　The　present　study　offers　valuable　insights　into　the　design　of　efficient　photocatalysts　for　wastewater　purification.　©　2024　Elsevier　Inc.