This book constitutes the refereed proceedings of the 23rd International Conference on Modeling Decisions for Artificial Intelligence, MDAI 2026, held in Vic, Spain, during September 7–9, 2026.

The 31 full papers included in this volume were carefully reviewed and selected from 80 submissions. The papers cover the following topical sections: Aggregation Operators, Fuzzy Measures and Integrals; Uncertainty and reasoning; Privacy and security; and Data science.