Abstract <p>Defect engineering has emerged as an effective strategy for enhancing the performance of photocatalysts by modifying their intrinsic properties. This review examines the synergistic effects of mixed defects (specifically vacancies, dopants, and planar defects) on photocatalytic efficiency by exploring recent advancements in their introduction, characterisation, and interaction. We highlight their reported impact on light absorption, charge transfer, and surface catalytic reactions. Specifically, point defects, such as vacancies and dopants, are known to introduce localized electronic states that can facilitate charge carrier kinetics, enhance light absorption, and catalyse surface reactions. Planar defects, including stacking faults, grain boundaries, and twin boundaries, can markedly alter charge carrier transport and, in some instances, are associated with augmented light absorption. The synergy between defect types and their collective influence on photocatalytic processes is discussed based on recent studies. The study delineates potential research directions and challenges in this field. Through these mechanisms, defect engineering offers pathways to address limitations of pristine and multi-component semiconductors and supports the development of advanced photocatalytic materials.</p> Graphical abstract <p></p>