This book constitutes the refereed proceedings of the 16th International Conference on Flexible Query Answering Systems, FQAS 2025, held in Burgas, Bulgaria, during September 11–13, 2025.The 26 full papers presented were carefully reviewed and selected from 49 submissions. The proceedings also include 3 invited talk and 2 tutorial papers. They were organized in the following topical sections: Invited Talks; Flexible Query Answering Systems; Data-driven Quality Management and Intelligent Systems for Academic Processes and Flexible Decision-making; Language Models in Advanced Information Retrieval; Intuitionistic Fuzzy Approaches for Flexible Querying and Reasoning under Uncertainty; and Emerging Trends in Flexible Query Answering and Information Retrieval.