This book constitutes the refereed proceedings of the 27th International Conference on Information Integration and Web Intelligence, iiWAS 2025, held in Matsue, Japan, during December 8–10, 2025. The 23 full papers, 12 short papers and 1 keynote paper included in this book were carefully reviewed and selected from 79 submissions. They were organized in topical sections as follows: Keynote; Foundations of AI and Data Intelligence; Knowledge, Reasoning, and Human Interaction; Emerging Technologies and Applied Innovation; Creative and Generative AI.