This book constitutes the refereed proceedings of the 98th International Symposium on Integrated Uncertainty in Knowledge Modelling and Decision Making, IUKM 2021, held in Ishikawa, Japan, in March 2022.

The 30 full papers presented were carefully reviewed and selected from 46 submissions. The papers deal with all aspects of uncertainty modelling and management and are organized in topical sections on uncertainty management and decision making, optimization and statistical methods, pattern classification and data analysis, machine learning, and economic applications.