This volume constitutes the refereed proceedings of the 19th International Symposium on Neural Networks, ISNN 2025, held in Zhangye, China, during August 22–24, 2025. The 52 full papers were carefully reviewed and selected from 60 submission. They were organized in topical sections as follows: Design, Modeling and Application of AI Algorithms; Signal, Image, and Video Processing; Modeling, Analysis, and Implementation of Neural Networks; Control Systems, Robotics, and Autonomous Driving; Machine Learning Methods and Applications.