Artificial Intelligence (AI)-driven chatbots, such as ChatGPT, have significantly impacted education, especially for English as a Foreign Language (EFL) learners. However, there is paucity of empirical evidence concerning the role of chatbots in psycho-emotional constructs like well-being and emotion regulation. It is important to address this issue because it can further our understanding of the ways through which using ChatGPT affects psycho-emotional constructs in EFL learners. This study aimed to unpack the intersection between using ChatGPT and well-being, with a focus on the mediating role of emotion regulation in the EFL context of Iran. Using convenience sampling, 492 EFL learners (205 males and 287 females) were invited to complete validated scales measuring ChatGPT use, well-being, and emotion regulation. The outcomes of structural equation modelling revealed a strong mediation effect of emotion regulation in the relationship between using ChatGPT and well-being. Additionally, significant positive correlations were found between using ChatGPT and both well-being and emotion regulation. Besides, a significant positive relationship was established between emotion regulation and well-being among the EFL learners. The results imply that the integration of ChatGPT into the Iranian EFL learning environment can be beneficial, considering its positive correlations with both well-being and emotion regulation among the Iranian EFL learners.