South African undergraduate university students face many unique challenges that put them at risk of developing mental health concerns such as depression, anxiety, stress, suicidal ideation, and posttraumatic stress disorder. However, psychological well-being has been found to play an essential role when it comes to effectively coping with and adjusting to university life. This study aimed to identify the predictor variable(s) or combination(s) of predictor variables that explained a significant percentage of the variance in psychological well-being amongst undergraduate university students. A total of 1,191 students between the ages of 18 and 30 participated in the study. This was a non-experimental study using a cross-sectional correlational research design. The results from the hierarchical regression analyses indicated that adjustment to university life statistically and practically significantly contributed to the explanation of the variance of the following dimensions of psychological well-being: Positive Relations, Self-acceptance, and Purpose in Life. These findings suggest that interventions that target adjustment could be used to improve the psychological well-being of undergraduate university students.