This book constitutes the refereed proceedings of the 16th International Symposium on Advanced Parallel Processing Technologies, APPT 2025, held in Athens, Greece, during July 13–16, 2025.

The 17 full papers and 10 short papers included in this book were carefully reviewed and selected from 74 submissions. They were organized in topical sections as follows: Chip and Accelerators, Memory and Storage, Cloud and Networking, Design for LLM and ML/AI, Big Data and Graph Processing, and Secure and Dependable System.