This two-part proceedings volume constitutes the refereed proceedings of the 19th International Conference on Hybrid Artificial Intelligent Systems (HAIS 2024), held in Salamanca, Spain, during October 9-11, 2024. The 52 full papers were carefully reviewed and selected from 112 submissions. They were organized in topical sections as follows: Part I: Biomedical Applications, Data Mining and Decision Support Systems, Deep Learning, Evolutionary Computation and Optimization. Part II: HAIS Applications, HAIS Energy Applications, Image and Text Processing, Reinforced Learning.