This book constitutes the proceedings of the 8th International Joint Conference on Rules and Reasoning, RuleML+RR 2024, held in Bucharest, Romania, during September 16-18, 2024. The 12 full papers and 4 short papers included in this book were carefully reviewed and selected from 35 submissions. The RuleML+RR symposia were devoted to disseminating research, applications, languages, and standards for rule technologies, with attention to both theoretical and practical developments, to challenging new ideas and to industrial applications.