This study aims to investigate whether or not self-esteem plays a significant mediating role in the relationship between positive schemas and psychological well-being in university students. The research, which has a correlational model, was designed on the basis of the quantitative research methodology. The study group of the research consists of 515 university students who participated in the research voluntarily and who were studying at three different state universities in the Black Sea, Eastern Anatolia, and Marmara regions of Turkey. Of these students, 384 (=74.6%) were female, and 131 (=25.4%) were male. In addition, the ages of the students in the study group ranged from 18 to 40, and the mean age was calculated as x=21.62 (SD=2.98). The research data were collected using a battery of four different measurement tools: Personal Information Form, Positive Schemas Scale, Two-Dimensional Self-Esteem Scale, and Psychological WellBeing Scale. In the analysis of the data, first of all, erroneous and/or missing data were examined, and then normality analyzes were carried out. Then, descriptive statistics and correlation analysis were performed, respectively. Finally, in line with the main problem of the research, whether self-esteem has a significant mediating role in the relationship between positive schemas and psychological well-being in university students was tested with a regression-based mediation model. The results obtained from the research revealed that all the variables discussed within the scope of the study were positively and significantly related to each other, and that self-esteem was a significant mediating variable in the relationship between positive schemas and psychological well-being in university students.