Psychological well-being refers to the experienced quality of life and reflects the desired psychological performance and experience. The purpose of this study was to investigate the role of the prosocial behavior on improving the psychological well-being of university students by mediating role of positive emotions and moderating role of emotion regulation. The statistical population of the study included all students of Shahid Chamran University of Ahvaz studying in 2021-2022, 200 of whom were selected using the multi-stage cluster sampling. The data was analyzed based on the structural equation modeling method in SPSS24 and PLS3. The results revealed that the prosocial behavior has a positive and meaningful effect on the psychological well-being (β, = 0. 176 and P= 0. 016) and on the positive emotions (β,= 0. 304 and P <0. 001). The positive emotions mediated the relationship between the prosocial behavior and the psychological well-being (β,= 0. 110 and P <0. 001). Moreover, the interactive effect of cognitive reappraisal (one of the emotion regulation subscales) and prosocial behavior on the psychological well-being was positive and meaningful (β,= 0. 203 and P <0. 001). Prosocial behavior, along with adaptive emotion regulation strategies, facilitates students' psychological well-being by creating positive emotions. Therefore, the positive consequences of prosocial behavior, in addition to affecting others, affect the actors, even though they do not expect it.