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.