Today's university town of Siegen(Sigena) was first mentioned in a document in 1079. A historic town center with buildings from the 17th and 18th centuries characterizes the image of the town. High-level educational institutions can be traced back to 1595 (foundation of the "Hohe Schule" of the state of Nassau). Before the university was founded in the 1970s, the Siegerland region already had a wide range of modern universities built in the 19th and 20th centuries with an engineering, economics and educational focus. The state government wanted to bundle this expertise in a new, more research-oriented structure. The University of Siegen was thus founded in 1972 - initially as one of five new comprehensive universities (Siegen, Wuppertal, Essen, Duisburg, Paderborn) in NRW. It has been officially known as the University of Siegen since 2003.

From the very beginning, psychology has played an important and very active role in the development and expansion of the University of Siegen as a modern, research-oriented discipline. This is also evidenced by its broad range of subjects, with individual subject areas being represented by several professors. In the 1990s and early 2000s, Psychology had 8-10 professorships, 3 senior academic positions and up to 7 staff positions. Further teaching assignments supplemented the program. At that time, research and teaching were realized through a diverse network of teaching and research collaborations with other disciplines. In terms of content, the psychologists focused early on the basic subjects of general psychology, social psychology, developmental psychology, differential psychology and the applied subjects of educational psychology, clinical psychology, organizational psychology, media psychology, health psychology and forensic psychology. Nevertheless, the opportunity to expand the subject was not seized. As a result, five newly appointed psychology professors left the university within a short period of time between 2003 and 2010. At the same time, the subject underwent a massive reduction in staff between 2003 and 2012 in favor of other disciplines. It was only the professors Angela Schorr, Kurt Sokolowski and Manfred Heck who succeeded in heralding a turnaround.

With the appointment of Simon Forstmeier, Andreas Kastenmüller and Tim Klucken as Professors of Developmental Psychology (now: Developmental Psychology and Clinical Psychology of the Lifespan), Social Psychology (now: Social and Economic Psychology) and Clinical Psychology (now: Clinical Psychology and Psychotherapy), the team was so scientifically strengthened that the founding of an Institute of Psychology (confirmed by the Rectorate in spring 2016) was initiated in 2015. A completely new, modern and innovative Bachelor's/Master's degree course in Psychology was quickly established, opening up a wide range of career paths in research and practice for future graduates. The first cohort of psychology students started in the 2018/19 winter semester. In the same year, the members of the Department of Psychology, together with the university management, responded to the new training regulations of the Psychotherapists Act of November 2019 with further expansion measures to ensure the training of psychotherapists at Bachelor's and Master's level up to licensure. A revised Bachelor's degree course in psychology, which meets the requirements of the law on the reform of psychotherapist training, started in the 2020/21 winter semester. The establishment of the professorships is progressing rapidly, and the planned move to new and historic buildings in the city of Siegen has already taken place in part. Numerous employees and doctoral students as well as Professor Julia Haberstroh (Psychological Aging Research), who was newly appointed in 2019, are now strengthening the young, cosmopolitan team, which has been joined by Junior Professor Kai T. Horstmann (Psychological Diagnostics and Differential Psychology) since the summer semester 2022. As part of the changes brought about by the new licensing regulations for psychotherapists, the Master's in Psychology with a focus on Clinical Psychology and Psychotherapy was launched in the winter semester 2023/24.