This book contains selected high-quality reviewed papers that have been accepted and presented at the 19th International Conference of Intelligent Unmanned Systems (ICIUS 2023), which was held in Adelaide, Australia, on 5-7 July 2023. The book is composed of articles that cover the advanced progress in unmanned systems, such as bio-inspired, underwater, aerial, and off-earth systems, as well as their subsystems, including control and navigation, communication, and machine vision systems. The book is suitable for researchers, engineers, graduates, and hobbyists who have interest in intelligent unmanned systems and their advances.