The present study aimed to examine the mediating role of emotion regulation and emotional suppression in the relationship between personality traits and addiction tendencies among university students. This research was a descriptive-correlational study. The statistical population consisted of all students at Kharazmi University during the academic year 2023-2024, from which 357 students were selected using convenience sampling. Data were collected using the NEO Five-Factor Personality Inventory (McCrae & Costa, 1992), the Emotion Regulation Questionnaire (Gross & John, 2003), and the Addiction Tendency Scale (Weid & Butcher, 1992). Data were analyzed using structural equation modeling with SPSS 24 and Amos 24 software. The results revealed that neuroticism had a direct and positive relationship with addiction tendency, while extraversion and conscientiousness showed a direct and negative relationship with addiction tendency. No significant direct relationship was found between agreeableness and addiction tendency. Furthermore, neuroticism had a direct relationship with emotional suppression, while extraversion and conscientiousness had a direct relationship with reappraisal of emotions. Reappraisal of emotional experiences was not significantly related to addiction tendency, but emotional suppression had a significant direct relationship with addiction tendency. Additionally, emotional suppression played a mediating role in the relationship between neuroticism and addiction tendency (t = 1.96). Therefore, personality traits, as well as emotion regulation and suppression, play a significant role in the tendency toward addiction among students. Targeting these two factors in psychological treatments may be effective in reducing students’ addiction tendencies.