This book constitutes selected papers from the 12th International Workshop on Rewriting Logic and Its Applications, WRLA 2020, held in Dublin, Ireland, in April 2020.Due to the COVID-19 pandemic the workshop took place virtually.The 11 full papers presented in this volume were carefully reviewed and selected from 16 submissions Rewriting logic is a natural model of computation and an expressive semantic framework for concurrency, parallelism, communication, and interaction. It can be used for specifying a wide range of systems and languages in various application fields.