This book constitutes the refereed proceedings of the 16th International Conference on Integrated Formal Methods, IFM 2019, held in Lugano, Switzerland, in November 2020. The 24 full papers and 2 short papers were carefully reviewed and selected from 63 submissions. The papers cover a broad spectrum of topics: Integrating Machine Learning and Formal Modelling; Modelling and Verification in B and Event-B; Program Analysis and Testing; Verification of Interactive Behaviour; Formal Verification; Static Analysis; Domain-Specific Approaches; and Algebraic Techniques.