This book constitutes the refereed proceedings of the 9th International Conference on Belief Functions, BELIEF 2026, held in Nanjing, China, during October 19–21, 2026. The 39 full papers included in this book were carefully reviewed and selected from 60 submissions. They were organized in topical sections as follows: Information Fusion; Deep Learning; Classification; Lifetime Prediction; Clustering; Large Language Models; Theory; and Decision Analysis and Hypothesis Testing.
