This book constitutes the refereed proceedings of the 9th International Conference on Applied Informatics, ICAI 2026, held in Orlando, FL, USA, during October 13–17, 2026.

The 45 full papers included in this book were carefully reviewed and selected from 126 submissions. They were organized in topical sections as follows: Artificial Intelligence; Data Analysis; Decision Systems; Image Processing; IT Architectures; Natural Language Processing; Security Systems and Virtual and Augmented Reality.