This book constitutes the refereed proceedings of the first International Conference on Cybersecurity, IoT, Data Science and Digital Forensics, CIDDF 2025, held in The Woodlands, Texas, USA, during October 2–4, 2025.The 13 full papers and one short paper included in this book were carefully reviewed and selected from 29 submissions. These papers focused on topics such as digital forensics and security analytics; the use of data science, machine learning, and visualization for security and forensic analysis; multimodal AI and intelligent systems; and IoT and system security.