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: Large Language Models and Prompting; Transformers and Representation Learning; Graph Neural Networks and Knowledge Representation; Generative Models and Diffusion.