This book constitutes the proceedings of the 27th International Conference on Implementation and Application of Automata, CIAA 2023, held in Famagusta, North Cyprus, during September 19–22, 2023.

The 20 regular papers presented in this book together with invited talks were carefully reviewed and selected from 30 submissions.

The topics of the papers cover various fields in the application, implementation, and theory of automata and related structures.