This book constitutes the proceedings of the 21st International Conference on Formal Engineering Methods, ICFEM 2019, held in Shenzhen, China, in November 2019.

The 28 full and 8 short papers presented in this volume were carefully reviewed and selected from 94 submissions. They deal with the recent progress in the use and development of formal engineering methods for software and system design and record the latest development in formal engineering methods.