This book constitutes revised selected papers from the 11th International Workshop on Engineering Multi-Agent Systems, EMAS 2023, which was held in London, UK, during May 29-30, 2023. The 11 full papers and 7 short papers included in this volume were carefully reviewed and selected from a total of 25 submissions. They were organized in topical sections as follows: agent-oriented software engineering; agents and microservices; strategy, reasoning, and planning; engineering domains and applications; agents in hypermedia environments; frameworks, tooling, and devops.