This book constitutes the refereed proceedings of the 20th International Conference on Integrated Formal Methods, IFM 2025, which took place in Paris, France, during November 19-21, 2025.
The 23 full papers presented together with 1 invited paper in this volume were carefully reviewed and selected from 69 submissions. The conference focuses on all aspects of formal methods, including deductive verification, model checking, reachability analysis, model-based testing, synthesis, timing and stochastic modelling, cyber-physical systems, autonomous systems, security and blockchain.