This book constitutes the refereed proceedings of the 26th International Conference, PDCAT 2025, held in Gold Coast, QLD, Australia, during November 22–24, 2025.The 47 full papers presented in this book were carefully selected and reviewed from 158 submissions. The PDCAT 2025 covers a broad spectrum of topics, including but not limited to parallel and distributed systems, cloud and edge computing, high-performance computing, resource scheduling and optimization, machine learning systems, data-intensive applications, networking, security, and privacy-preserving computation.