This book constitutes the proceedings of the Third International Workshop on Dynamic Logic, DaLi 2019, held in Prague, Czech Republic in October 2020. Due to COVID-19 the workshop has been held online. The 17 full papers presented together with 6 short papers were carefully reviewed and selected from 31 submissions. The theoretical relevance and practical potential of dynamic logic is a topic of interest in a number of scientific venues, from wide-scope software engineering conferences to modal logic specific events. The DaLi 2020 workshop is exclusively dedicated to Dynamic logic and aims at filling this gap and creating a heterogeneous community of colleagues, from Academia to Industry, from Mathematics to Computer Science.