The IntelITSIS-2025 focuses on all technical and practical aspects of the latest research and results of international scientists and practitioners related to intelligent information technologies, and information security systems. This workshop provides opportunities to exchange new ideas, to establish business or research relations and to find global partners for future collaboration. 6th International Workshop on Intelligent Information Technologies & Systems of Information Security received 74 submissions from Ukraine and the world. All papers were evaluated by two or three reviewers. Based on the reviews, a rating of papers was compiled. Papers with a positive average scores were accepted for presentation at the Workshop. According to the decision of the International Program Committee, 29 papers were accepted for presentation at the Workshop. So, final acceptance rate is 39%. The IntelITSIS-2025 joined scientists from Ukraine, United Kingdom, USA, Slovakia, Czech Republic, Austria, Poland, Estonia, Egypt, Algeria, China. In general, the representatives from 21 Universities from around the world and 18 Ukrainian Universities (summary 39 institutions) took part in the Workshop. We would like to thank the members of International Program Committee and Organizing Committee, and external reviewers for their excellent and tireless work. We sincerely thank everyone for a fruitful work and interesting presentations! We hope that the workshop results make a significant contribution to the development of intelligent information technologies, and information security systems in Ukraine and in the world.