This book constitutes the refereed proceedings of the 23rd International Conference on Mathematical Optimization Theory and Operations Research, MOTOR 2024, held in Omsk, Russia, during June 30 - July 6, 2024. The 30 full papers included in this book were carefully reviewed and selected from 79 submissions. This book also contains two invited talk. They were organized in topical sections as follows: mathematical programming; combinatorial optimization; game theory; and operations research.