This volume constitutes the revised selected papers of the 29th International Workshop on Coordination, Organizations, Institutions, Norms, and Ethics for Governance of Multi-Agent Systems, COINE 2025, held in Detroit, MI, USA, on May 20, 2025. The 8 full papers were carefully reviewed and selected from 16 submissions. They were categorized under the following topical sections: Norm Dynamics and Coordination; Institutions and Regulations; Large Language Models and Social Reasoning.