This book constitutes the refereed proceedings of the 17th Conference on Optimization and Information Systems, COSI 2025, held in Bejaïa, Algeria, during June 1&3, 2025. The  45 papers were accepted, including 12 short papers and 33 full papers , among which 27 finally included in this volume were carefully reviewed and selected from 81 submissions.They are organized into the following topical sections: Artificial Intelligence,Operational Research and Decision Support Systems and Cybersecurity and Applications.