This LNCS 14627 conference volume constitutes the proceedings of the 16th International Symposium on NASA Formal Methods, NFM 2024, held in Moffett Field, CA, USA in June 2024. The 20 full papers together with 6 short papers included in this volume were carefully reviewed and selected from 68 submissions. The conference focuses on the on formal techniques for software and system assurance for applications in space, aviation, robotics, and other NASA-relevant safety-critical systems.