This book constitutes the refereed proceedings of the 8th International Symposium on Combinatorial Optimization, ISCO 2024, held in La Laguna, Tenerife, Spain, during May 22-24, 2024. The 30 full papers included in this book were carefully reviewed and selected from 46 submissions. They were organized in topical sections as follows: integer programming; graph theory; parameterized algorithms; approximation algorithms; integer programming for machine learning; and applications.