The present study aimed to examine the mediating role of basic psychological needs in relationship between emotion regulation and vitality in friendships among university students aged 18 to 25. This correlational study investigated the relationships between variables using path analysis. In a correlational design, a total of 150 undergraduate students from Bahar Institute of Higher Education in Mashhad, Iran, were selected using convenience sampling method during the second semester of the 2024–2025 academic year. Data were collected using the Emotion Regulation Inventory (ERI), the Basic Psychological Need Satisfaction in Relationships Scale (BNS-RS), and the Subjective Vitality Scale (SVS). The results indicated that the direct effects of integrated regulation on the need for competence, as well as on the needs for autonomy, competence, and relatedness to vitality in friendships, were positive and significant. The direct effects of suppressive regulation on psychological needs and vitality in relationships were also negative and significant. Dysregulated regulation had a direct, negative, and significant effect on the need for autonomy and relatedness (P < 0.05). The indirect effects of emotion regulation on vitality in friendships, mediated by basic psychological needs, were significant. It appears that emotion regulation, by influencing the fulfillment of basic psychological needs, can affect individuals' vitality in young adulthood. Accordingly, enhancing emotion regulation strategies may facilitate increased vitality in friendships.