The present study belongs to a new strand of research in learning in higher education focusing on emotions and emotion regulation, including defense mechanisms. The purpose of the study was to investigate the mediating role of implicit and explicit emotion regulation in the relationship between academic emotions and approaches to learning. Participants were composed of 226 undergraduates (40 males and 186 females studying in a social science department). They completed the following questionnaires: Emotion Regulation Questionnaire, Student Experience of Emotions Inventory, Defense Style Questionnaire, and Approaches to Learning and Studying Inventory. Both the moderating (interaction) and the mediational (indirect) effects were examined using the PROCESS program. Results failed to indicate the moderating role of emotion regulation in the association between academic emotions and approaches to learning. Instead, results revealed the dominant mediating role of emotion regulation and particularly the role of immature defense style in the relationship between negative emotions and approaches to learning. Moreover, reappraisal and suppression seemed to act as mediators in the relationship between positive and negative emotions with deep and surface approaches, respectively. The results of the study are discussed in the context of the recent literature. Implications for higher-education institutions regarding the role of unconscious cognitive processes are also discussed.