||Defects are ubiquitous in ceramic materials, and can fundamentally alter their chemical, physical, optical, thermal and electronic properties as well as their coupling with each other. Many opportunities exist for defect engineering in electroceramics to tune their properties—at not only the ground state but also excited states under external fields and stimuli—specially in a controlled manner. For example, active research in recent years has converted the otherwise inert transition metal oxides and two-dimensional layered materials to new (photo-)electrochemical active materials by dynamically controlling the oxygen defect concentration and distribution (ordered or disordered) to couple existing physical properties. Nevertheless, harnessing functional defects in electroceramics presents continuous important scientific and technological challenges to materials scientists and engineers; advanced theoretical, simulation and experimental tools are urgently required to characterize, visualize, understand, predict, and control formation and migration of defects and interactions between them. Yet these techniques are largely limited or in some cases unavailable at present. To address the pressing needs and challenges, this symposium aims at highlighting the most recent developments, applications, and forefront breakthroughs in harnessing functional defects in a wide range of electroceramic materials via bridging expertise on theoretical modeling/simulation, materials synthesis, functional measurement/control, and advanced characterizations. Particular attention will be paid to high-throughput studies combining simulations and experiments, predictive modeling of defect physics and chemistry, and the synthesis, control, and advanced characterizations of functional defects in electroceramic materials. This topic may also include novel architectures for studying defects, such as the use of epitaxial heterostructures. Also of interest are, in-situ or operando monitoring of functional defect formation/migration/ordering, the interplay between defect responses in ionic lattices and their manipulation by external fields, and use of transformative imaging capabilities to probe defect-driven phenomena in-situ along with their dynamics. This symposium will provide an interactive forum for scientists from various fields interested in defect engineering for both classical and emerging applications. Specific sessions will be organized based on scientific theme topics in order to foster cross-fertilization of ideas and strategies. We will also host sessions with a focus on recent methodological advances in studying point and extended defects in functional materials. We hope this symposium will benefit ceramists with various backgrounds, and will help encourage the implementation of predictive design, smart synthesis/control and advanced characterization approaches to solve the urgent problems in this field.