Insecure attachment is believed to play a fundamental role in non-suicidal self-injury (NSSI). In fact, the quality of parent–child attachment relationships has become an emerging topic attracting a growing number of theoretical and research contributions in the field of NSSI. However, despite these considerable advances in the scientific study of NSSI, progress pertaining to investigating the quality of romantic attachment relationship is lacking. In an effort to expand current knowledge, the present study aims to not only explore the relationships between romantic attachment and NSSI, but also to explore the mechanisms by which these two variables relate by examining the mediating role that emotion regulation and dyadic coping might play in this relationship. Participants consisted of 797 (81.9 % female) university students, all of whom were involved in a romantic relationship for at least 6 months and between the ages of 17 and 25. Results revealed that although difficulties in emotion regulation mediated the relationships between romantic attachment insecurity (i.e., attachment anxiety and avoidance) and NSSI, dyadic coping was not found to be a significant mediator. These results highlight the importance of attachment security and internal processes to manage stress in the prevention of NSSI.