This book constitutes the refereed post-conference proceedings of the Fourth International Conference on Applied Intelligence and Informatics, AII 2024, held in London, United Kingdom, during December 18–20, 2024.

The 34 full papers included in these proceedings were carefully reviewed and selected from 118 submissions. They are organized in these topical sections as follows:Application of AI and Informatics in Pattern Recognition and Application of AI and Informatics in Network, Security,and Analytics.