This book constitutes the refereed proceedings of the 26th International Conference on Product-Focused Software Process Improvement, PROFES 2025, held in Salerno, Italy, during December 1-3, 2025.

The 9 Industry papers, 19 Workshop papers, 1 Doctoral symposium paper and 1 Tutorial paper presented in this volume were carefully reviewed and selected from 101 submissions. The contributions were organized in topical sections as follows: Industry papers; Doctoral symposium papers; Tutorial papers; First International Workshop on Analytics for Software Product and Process Improvement (A-SPPI 2025); First International Workshop on Promoting and Dealing with Advanced Technology in Healthcare (PATH 2025); and First International Workshop on Quality Evaluation of ML-based Software Systems (QUEMALES 2025).