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.