This book constitutes the refereed proceedings of the 39th International Conference on Industrial, Engineering and Other Applications of Applied Intelligent Systems on Advances and Trends in Artificial Intelligence, IEA/AIE 2026, held in Kuala Lumpur, Malaysia, July 6–8, 2026.The 99 full papers and 8 short papers included in this book were carefully reviewed and selected from 210 submissions. They focus on the following topical sections: Industry, Manufacturing and Fault Diagnosis; Security, Privacy and Trustworthy AI; Reinforcement and Multi-Agent Learning; Machine Learning Methods and Evaluation; Adaptive Learning and Contrastive/Energy-Based Methods; Fuzzy Systems, Optimization and Emerging Applications.